Eaton Arc-Resistant Magnum PXR Low-Voltage Switchgear

General Description

This design guide provides detailed information on Eaton Arc-Resistant Magnum PXR low-voltage switchgear, which protects operating and maintenance personnel from dangerous arcing faults by channeling arc energy out the top of the switchgear. This equipment is designed for low-voltage power distribution and control systems, specifically for switchgear applications.

Product Description

Arc-Resistant Switchgear

Arc-resistant low-voltage switchgear protects personnel by channeling arc energy safely out the top of the unit. Arcing faults, caused by human error or insulation failure, can generate extreme thermal energy and blast forces. While arc-resistant gear does not prevent these arcs, it safely redirects and contains them regardless of the origin. Magnum PXR switchgear has been tested in all three compartments for 0.5 seconds, passing IEEE® Type 2B standards at 100 kA at 508 V and 85 kA at 635 V. Both indoor rear access and indoor front access constructions are available as arc-resistant Type 2B.

Image: Eaton Arc-Resistant Magnum PXR Low-Voltage Switchgear assembly.

Accessibility Types

Eaton arc-resistant switchgear is Type 2B. Its performance is defined by accessibility type in accordance with IEEE test guide C37.20.7:

• Type 1: Switchgear with arc-resistant designs or features at the freely accessible front of the equipment only.
• Type 2: Switchgear with arc-resistant designs or features at the freely accessible exterior (front, back, and sides) of the equipment only. (Type 2 incorporates Type 1.)
• Type 2B: Switchgear with Type 2 accessibility plus arc-resistant in front of the instrument/control compartment with the instrument/control compartment door opened. (Type 2B incorporates Type 2.)

Normal Operating Conditions

Eaton arc-resistant switchgear is Type 2B. The instrument/control compartment door and breaker secondary door can be open while maintaining Type 2B protection. Arc-resistant features provide additional protection to personnel performing normal operating duties near energized equipment. Proper application requires:

• All breaker doors and rear covers are properly closed and latched.
• Pressure relief devices are free to operate.
• Fault energy available to the equipment does not exceed its rating (short-circuit current and duration).
• No obstructions around the equipment that could direct arc fault products into an unprotected area.
• The equipment is properly grounded.

Users should also refer to documents like NFPA 70E® for safety training, work practices, and methods of evaluating safe work distances from energized equipment, flash hazard potential, and proper PPE when working on or near energized equipment with doors/covers open or unsecured.

Product Offering

Arc-resistant switchgear comes standard with:

• Type 2B construction, including breaker secondary compartment.
• Up to 100 kA short circuit at 508 Vac maximum and 85 kA short circuit at 635 Vac maximum.
• Up to 10,000 A horizontal main bus continuous current.
• Up to 5000 A vertical bus continuous current.
• Magnum circuit breakers with Power Xpert Release (PXR) trip units, with frame ratings between 800 A and 6000 A.
• Up to four high breaker configuration.
• Requires 10-foot equipment base to ceiling clearance.
• Additional safety without increasing the footprint of regular Magnum PXR switchgear.
• Indoor rear access construction available.
• Indoor front-access construction available.

Standard Features

• IEEE Type 2B arc-resistance: Regardless of whether the arc originates in the breaker, bus, or cable compartment.
• Stronger door and latch: Robust doors made of heavy 12-gauge metal, secured with two-point latches.

Image: Close-up of breaker bellows and two-point door latch mechanism.

• Breaker bellows: Bellows surround the breaker door, preventing arc gases from escaping around the nose of the breaker while ensuring easy racking of the breaker into the disconnected position.
• Rear dynamic flap system: Ventilation openings in the breaker are open during operation for proper equipment ventilation, and then sealed off during an arc event. This gravity-based system closes flaps during an arcing event due to arc pressure wave, with no electrical parts that could break or fail.

Image: Rear dynamic flap system with ventilation openings.

• Ventilation system: Each breaker compartment is vented to allow ionized gas to flow into the bus compartment from any location in the switchgear and then exit through the hinged flaps.
• Bottom or top cable or bus duct entry.
• Cable compartment floor plates.

Optional Features

• Plenum: Mounted on top of arc-resistant gear to direct dangerous arc gases. The exhaust duct can be attached to the side, rear, or top. A 4-foot restricted area is recommended from the exhaust duct exit.
• Zone selective interlocking protection: Allows the breaker closest to the fault to trip without preset time delay, keeping the rest of the distribution system online.
• Arcflash Reduction Maintenance System™: Enhances safety.
• Safety shutters: Provides additional protection.
• One piece hinged and bolted rear panel: For easy access.
• Insulated bus: Improves safety and reliability.
• Vented bus/cable compartment barriers: Available vented to allow arc gas flow during an arc event.
• Cable compartment segregation barrier: Separates cable compartment.
• Integral Motorized Remote Racking (MR2): Allows remote racking of the breaker in and out without stepping into the arc flash zone.
• GearGard™ for low-voltage switchgear: Optional environmental sensing and protection package providing alarms for abnormal environmental conditions. Activates heaters when nearing dew point to prevent condensation. Also provides operating environment condition level for maintenance plans following NFPA 70B.
• Thermal Monitoring: A more budget-friendly version of GearGard, focused on continuous thermal monitoring to detect potential and intermittent issues missed by standard infrared windows.

Standards and Certifications

• UL® 1558/UL 1066
• IEEE C37.20.1, C37.13, C37.20.7
• CSA C22.2 No 31-04, C22.2 No. 0.22
• ANSI C37.51
• Third-party UL witnessed and certified

Ratings

Table 20.10-1. Voltage Ratings (AC)

Table 20.10-2. Available Bus Ratings

Overview

Eaton's Magnum PXR switchgear, backed by 70 years of development, sets industry standards for quality, reliability, maintainability, and extended operating life in low-voltage electrical distribution systems. It is designed to meet changing customer needs by providing:

• Lower installation and maintenance costs.
• Higher interrupting ratings and withstand ratings.
• Better coordination capability.
• Increased tripping sensitivity.
• Enhanced safety measures.
• Higher quality, reliability, and maintainability.
• Communications and power quality monitoring and measuring capabilities.
• Flexible layouts that maximize capital use by minimizing equipment footprint.

Magnum PXR switchgear meets needs for general applications, service entrances, harsh environments, multiple source transfers, and special grounding systems. With a modern design, it provides:

• 100% rated, fully selective protection.
• Integral microprocessor-based breaker tripping systems.
• Easy-to-follow programming and secondary injection testing via micro-B USB connection and Power Xpert Protection Manager (PXPM) software.
• Two-step stored-energy breaker closing.
• Standard 100 kA short-circuit bus bracing.
• Optional 150 kA short-circuit bus bracing.
• Optional metal barriers to isolate the cable compartment from the bus compartment.
• Full range of safety solutions for arc flash hazard and operator error.

Additional features for coordinated, safe, convenient, trouble-free, and economical control and protection of low-voltage distribution systems are also provided.

Magnum circuit breakers with PXR are designed to conform to:

• IEEE Standards C37.13, C37.16, C37.17
• ANSI Standard C37.50
• UL 1066
• CSA C22.2 No. 268

Magnum PXR switchgear conforms to the following standards:

• CSA C22.2 No. 31-10, C22.2 No. 0.22
• IEEE C37.20.1, C37.20.7
• ANSI C37.51
• UL 1558
• American Bureau of Shipping (ABS)
• Built in an ISO® certified facility

Maximum ratings for Magnum PXR switchgear are 600 Vac, 10,000 A continuous cross bus.

Seismic Qualification

Refer to eaton.com/seismic for information on seismic qualification for this and other Eaton products.

Structure Features

• Standard finish: Gray paint finish (ANSI 61) using a modern, completely automated, and continuously monitored electrostatic powder coating system. This system includes spray de-grease and clean, spray rinse, iron phosphate spray coating, non-chemical seal, oven drying, electrostatic powder spray paint coating, and oven curing.
• Integral base: Ruggedly formed base increases rigidity, reduces installation damage, and is suitable for rolling, jacking, and handling. A lifting angle is permanently welded into the bus compartment structure for increased strength. Bottom frame members are indented to allow pry bar insertion.
• Heavy-duty door hinges: Allow easy access to the breaker internal compartment for inspection and maintenance.
• Breaker door interlock: Prevents access to potential live parts when the switch is ON. Does not engage in TEST position to avoid interference during testing and commissioning.
• Rear cover/doors: Standard rear bolted covers are provided, split into two sections for easier handling. Optional rear doors are available.
• Through-the-door design: Allows functions like levering the breaker, operating manual charging, viewing spring charge status, closing/opening the breaker, viewing/adjusting the trip unit, and reading the breaker rating nameplate without opening the circuit breaker door.

Image: Close-up of a Magnum PXR breaker showing through-the-door operational elements.

• Cassette design: Supports the breaker in the cell and on movable extension rails, allowing the breaker to be drawn out without de-energizing the entire switchgear lineup.
• Modified clawshaft: Clawshaft arms are reversed and shifted inboard to serve as a rejection feature against Magnum DS breakers, preventing incorrect installations.
• Accessibility: When the door is open or removed, each breaker compartment provides front access to isolated, vertical wireways, primary disconnects, cell current transformers, and other accessories for ease of field wiring and troubleshooting.
• Four-position drawout: Breakers can be in connected, test, disconnected, or removed positions. Movement between connected, test, and disconnected positions is possible with the compartment door closed.
• Closing spring automatic discharge: Mechanical interlocking automatically discharges closing springs when the breaker is removed from the test to the disconnect position.
• Optional safety shutters: Positive acting safety shutters isolate breaker connections to the main bus when the breaker is withdrawn, reducing potential for accidental contact with live bus. Insulating covers ("boots") are furnished on live main stationary disconnecting contacts in compartments equipped for future breakers.
• Breaker inspection: When withdrawn on the rails, the breaker is completely accessible for visual inspection; tilting is not necessary. Rails are permanent parts of every breaker compartment.

Bus Features

• Interference interlocks: Supplied on breakers and in compartments of the same physical size to ensure an incorrect breaker cannot be inserted.
• Optional key interlock (switchgear mounted): Holds the breaker cell mechanically trip-free to prevent electrical or manual closing. Breaker can be stored in compartment or removed for maintenance/spare use without disturbing the interlock. No breaker modification is required.

Buses and connections

Vertical and cross bus ratings in Magnum PXR switchgear are based on UL and IEEE standard temperature rise of 65 °C above a maximum ambient air temperature of 40 °C.

• Bus ampacities: Vertical and main bus ratings in Magnum PXR are 1600, 2000, 3200, 4000, and 5000 A. Main bus ratings up to 10,000 A are available. Vertical section bus is sized per main cross bus maximum rating or by IEEE C37.20.1 to a maximum of 5000 A.
• Bus bracing: Standard bracing is 100 kA. The "U" shaped bar is the core of the Magnum PXR vertical bus, providing high mechanical strength. Tested to withstand 85 kA short-circuit for 60 cycles.
• Silver and tin plating: Bolted, silver-plated copper bus is standard, with plating over the entire length of the bar. Optional tin-plated copper bus is available.
• Bus joints: All joints are bolted and secured with Belleville-type spring washers for maximum joint integrity, reducing loosening due to temperature variations. Optional maintenance-free hardware is also available.
• Full neutral: For four-wire applications, the neutral bus is rated 100% of main bus rating as standard. Neutral ratings up to 10,000 A are available as an option. Four-pole breakers can be used with four-wire systems.
• Ground: A ground bus is furnished the full length of the switchgear assembly, fitted with terminals for purchaser's connections.
• Glass reinforced polyester and standoff insulation system: This industry-proven material provides exceptional mechanical and dielectric withstand strength, high resistance to heat, flame, and moisture. Substantial testing demonstrates superior performance for decades of trouble-free operation.
• Optional epoxy bus coating: For harsh environments, optional conductor insulation covering is available. Applied during bus assembly, it covers all vertical and horizontal phase bus bars. Removable boots provide access to section-to-section bus joints for inspection and maintenance.
• Barriers: Optional grounded metal barriers isolate the main bus and connections from the cable compartment, providing added safety and reducing potential for objects falling into the bus compartment. Vertical barriers between cable sections can be added. Barriers are removable for bus compartment access. They can be solid metal or vented for infrared scanning.

Image: Interior view of optional bus compartment and vertical section barriers.

Image: Insulated bus bars within the switchgear.

Wiring Features

• Cable compartment: Provides ample room for terminating power cables. Removable top roof sheets allow for easy conduit hub installation. The floor is open for cable entry from underground duct banks. Optional floor plates are available. Pow-R-Way® busway and nonsegregated bus duct can be terminated.
• Lug pad: Lugs are on breaker run-backs, accommodating 45° angle lug orientations to reduce cable bending radius, installation, and maintenance time. Mechanical setscrew type lugs are standard. Optional NEMA two-hole compression lugs are available.
• Control wireway: An isolated vertical wireway is provided for routing factory and field wiring in each switchgear section. Breaker secondary terminal blocks are standard (30 A, #22-#10 wire size). Extruded loops are punched in side sheets for securing customer control wiring without adhesive wire anchors.
• Control circuits can be wired in all cells without removing the circuit breaker. Power circuits can be connected in the rear simultaneously with control circuits in the front.
• Control wire: Standard wire is Type SIS insulated stranded copper, extra flexible No. 14 AWG minimum. Type VW-1 wire is available.
• Control wire marking: Each wire is imprinted with UV-cured ink for durability and easy identification. Imprinting every 3.00 inches (76.2 mm) includes origin zone/wire name/destination zone. "<" indicates wire origination, ">" indicates wire destination. Optional sleeve type or heat shrink sleeve type marking is available.

Image: Example of control wire marking with origin/wire name/destination zone format.

• Secondary terminal compartment: 84 finger-safe secondary connections for standard frame Magnum PXR breaker, 72 for narrow frame. Customer's secondary terminal connections are at the front, behind a separate door.
• Short-circuiting terminal blocks: One provided for each set of instrumentation or relaying application current transformers.
• Shipping split connection: At each shipping split, control connections are made with plug-in terminal blocks (600 V, 30 A). Blocks mechanically interlock without removing line or load connections, increasing installation speed and reducing incorrect connections.

Instrumentation/Metering Features

• Flexibility: Magnum PXR switchgear allows for a variety of metering options.
• Analog switchboard type meters: Such as ammeters and voltmeters.
• Electronic power metering: Such as Power Xpert Quality (PXQ) event analysis system and Power Xpert Energy (PXE) meters.
• Instrument compartments: White interior panels for ease of visibility.

See eaton.com/meters for Metering and Power Management products.

• Voltage transformers: Rated 10 kV BIL, protected by primary and secondary fuses (current-limiting primary fuses).
• Current transformers: For metering and instrumentation, mounted in breaker compartments, front accessible. Secondary wiring is color-coded. Bus-mounted CTs are available.
• Control power transformers: Provided for AC control of circuit breakers, space heaters, and/or transformer fans. Protected by current-limiting primary fuses. Supplementary fuses and circuit breakers protect branch circuits on the secondary side.
• Instrument compartment door: Devices not fitting on the secondary terminal compartment door are mounted on the instrument compartment door.
• Instrumentation—secondary terminal compartment door: Devices like control pushbuttons, indicating lights, switches, and analog meters can be mounted on these panels within space limitations.

Image: Secondary terminal compartment door with control pushbuttons, indicating lights, and switches.

Accessories and Options

Switchgear accessories

Standard accessories furnished with each Magnum PXR switchgear assembly include:

• One breaker racking tool.
• Insulating covers or "boots" furnished on live main stationary disconnecting contacts in compartments equipped for future breakers.
• Removable cover to block opening in the door when the breaker is temporarily removed from its compartment.

Optional Accessories

• Traveling type circuit breaker lifter: Rail-mounted on top of switchgear.
• Floor-running portable circuit breaker lifter and transfer truck: With manual lifting mechanism. Requires approximately 84.00 inches (2133.6 mm) deep front aisle space.
• Test cabinet: For electrically operated breakers, with pushbuttons, control cable, and receptacle, for separate mounting.
• Optional space heaters: To be placed in the bottom of the breaker, cable, and bus compartments.
• Remote racking device (MRR1000): For both breaker racking and operation (open/close) from a safe distance. Mounts to any existing Magnum circuit breakers with Power Xpert Release trip units. Uses standard 120 V, 15 A, single-phase, 60 Hz supply.

Image: Magnum PXR shutter module.

Image: Optional switchgear-mounted lifter for circuit breakers.

Image: Cable lashing device.

Image: MRR1000 remote racking device with control panel.

Enhanced Switchgear Options

• Optional integrated motorized remote racking device (MR2): Can be installed on any breaker and controlled via a PXG1000 with the remote racking application or a remote pendant.
• Optional environmental sensing and protection package: Provides alarms for abnormal environmental conditions. Activates heaters (online and offline) when nearing dew point to prevent condensation. Also provides operating environment condition level for maintenance plans following the 2023 revision of NFPA 70B standard.
• Infrared scanning windows: For thermal scans of lug landings.
• Maintenance-free (Torque-&-Forget) bus hardware.
• Optional thermal monitoring system: Allows users to detect potential issues before they become a problem, and intermittent issues missed by standard infrared windows, with 24/7 monitoring.
• Grounding balls and covers: For protecting maintenance personnel downstream of switchgear feeder breakers.
• Pendant: For remote open and close of electrically operated breakers.

Image: Grounding balls and covers for maintenance personnel protection.

Image: Remote control pendant for breaker operation.

Image: Magnum MR2 integral racking device with remote pendant.

Circuit Breakers

Eaton's Type MPS power circuit breakers are a complete, modern, and rugged line of low-voltage power circuit breakers utilizing Eaton's DE-ION® principle of arc extinction. The breaker family is distinguished by similar appearance and operation frame-to-frame. All frame sizes are either manually or electrically operated. For detailed information on Magnum PXR low-voltage power circuit breakers, refer to eaton.com/MagnumPXR.

Breaker Features

• Four Physical Frame Sizes: Narrow, standard, double narrow, and double to promote compact modular enclosures and improve enclosure density.
• Contacts: Magnum PXR has silver tungsten moving contacts and silver graphite stationary contacts. These provide a long-wearing, low-resistance joint. Contacts are protected from arcing damage by "heel-toe" action, where arcing contacts mate before main contacts part, striking the arc away from main contacts. Main contacts are butt type with multiple fingers for many points of contact without critical alignment.

Image: Magnum PXR breaker contacts with arc chutes removed.

Stored-Energy Mechanism

A cam-type closing mechanism closes the breaker, receiving energy from a spring charged by a manual handle or a universal electric motor. Stored energy is released by manually depressing a button or electrically energizing a releasing solenoid.

Image: Front view of a Magnum PXR circuit breaker.

Arc Chute

There are three basic means of extinguishing an arc: lengthening the arc path; cooling by gas blast or contraction; and deionizing or physically removing conduction particles. The DE-ION principle is incorporated in all Magnum circuit breakers with PXR, enabling faster arc extinguishing, positive interruption, and minimum contact burning.

Breaker Operation

Levering Mechanism

The worm gear levering mechanism is self-contained on the breaker drawout element and engages slots in the breaker compartment. A standard 3/8-inch (10 mm) drive set levers the breaker between connected, test, and disconnected positions. Mechanical interlocking prevents levering unless the breaker is in the opened position.

Protection During Levering Operation

When levering the breaker between connected, test, and disconnected positions, the operator is protected from live parts by the breaker door.

True two-step stored energy closing

Refers to the sequence required to charge and close the breaker:

1. Breaker closing springs are charged manually or by the optional charging motor. Mechanical interlock prevents closing until springs are fully charged.
2. With springs fully charged, the breaker can be closed by pressing the manual close pushbutton or by the optional spring release coil via a remote electrical signal.

"Stored energy" is energy held in waiting, ready to open or close the breaker within five cycles or less. The unique cam and spring design provides energy for a single close-open sequence and multiple charge-close operations (charge-close-recharge-open-close-open). Energy to open the breaker is always restored after a closing operation. Closing springs are interlocked with the breaker racking mechanism to ensure discharge before the breaker reaches the disconnect position.

Provisions for padlocking

All breakers include provision for padlocking open to prevent electrical or manual closing. This secures the breaker in connected, test, or disconnected positions by preventing levering.

Ease of inspection and maintenance

Magnum circuit breakers with PXR are designed for maximum accessibility and ease of inspection and maintenance.

Manually operated breakers

Equipped with a manual charging handle to charge closing springs. Manual closing and tripping pushbuttons operate the breaker. Remote closing and tripping can be accomplished by installing optional electric spring release and shunt trip coils. Closing springs must be charged manually before remote signals can be sent.

Electrically operated breakers

Equipped with a spring charging motor and electrically operated spring release and shunt trip coils. The manual charging handle can be used to charge springs when power is unavailable to the charging motor.

Optional Breaker Accessories

• Shunt trip device (ST): Provides remote electrically controlled breaker opening when energized by a rated voltage input.
• Spring charge motor (MOT): Charges breaker closing springs automatically, facilitating remote or local closing. Motor assembly includes a cut-off switch for external indication.
• Spring release device (SR): Provides remote electrically controlled breaker closing when coils are energized by a rated voltage input.
• Undervoltage release (UVR): Trips the breaker when existing voltage signal is lost or falls below a threshold.
• Auxiliary switch: Up to 12 Form C auxiliary individual dedicated contacts are available for customer use to indicate if the breaker is in the OPEN or CLOSE position.
• Mechanical trip indicator flag: Red flag pops out for local visual indication when the PXR trip unit acts to trip the breaker on an overcurrent condition. Available in interlocked (manually reset) and non-interlocked versions.
• Bell alarm/overcurrent trip switch (OTS): Provides two Form C contacts that change state when the PXR trip unit acts to trip the breaker. Contacts are available for external indication or customer use and are manually reset by the mechanical trip indicator.
• Padlockable pushbutton cover: Permits padlocking hinged cover plates to block access to buttons on the breaker faceplate.
• Mechanical operations counter: Records mechanical operations of the breaker over its installed life.
• Latch check switch: Provides one Form C contact that changes state when the breaker is ready to close. Can be wired to the spring release device for fast transfer applications or for external ready-to-close indication.
• Magnum MR2 integral racking: Magnum PXR or Power Defense SB (PD-SB) drawout breakers with the MR2 integral racking option allow remote racking from 30 ft (9.14 m) or greater. MR2 mitigates arc flash exposure. The system includes a breaker with integral motorized racking assembly, wired cassette, controller, and a customer-provided user interface. The racking assembly contains safety and component position sensing features. The controller accepts 120 Vac and supplies power to a motor based on user input. Breaker position is detected by three internal limit switches.

Magnum PXR Switchgear—Trip Units

Power Xpert Release trip unit

The Power Xpert Release (PXR) trip unit, with current sensors and a trip actuator, is the circuit breaker subsystem providing protection, monitoring, and metering functions. PXR analyzes signals from current sensors and voltage connections. If current level and time delay settings are exceeded, the PXR trip unit initiates a trip. Automatic overload and short-circuit tripping characteristics are determined by current rating and user-selected protection settings. Adjustments allow coordination and adaptation to any application. External control voltage is not required for current protection. All trip units have thermal memory, 50/60 Hz operation, and thermal self-protection at 90 °C.

PXR integral microprocessor-based breaker overcurrent trip systems

Provide maximum reliability with true rms sensing, excellent repeatability, and minimum maintenance. No external control source is required for protective functions.

Image: Front panels of PXR 20 and PXR 25 trip units.

Trip functions

Magnum PXR trip units provide maximum flexibility, available in LSI and LSIG configurations. Short delay or instantaneous functions can be defeated, reducing spare breaker inventories and maximizing interchangeable breaker usage.

• PXR 20: Enables up to nine phase and ground current protection settings for flexibility in trip-curve shaping and multi-unit coordination. Adds zone selective interlocking. Programmable via dials, LCD display, navigation buttons, micro-B USB, and PXPM software. Provides 0.5% accuracy current metering, ground fault enable/disable, and Arcflash Reduction Maintenance System.
• PXR 25: Provides programmability for more sophisticated distribution systems.

Image: Front panel of PXR 35 top-of-the-line trip unit.

• Increased protection and coordination capabilities.
• Systems monitoring information: power factor, voltage, current, harmonic distortion, waveform capture with LCD display.
• Four programmable contacts for customer use.
• Time stamping of trip events for improved troubleshooting and diagnostics.
• Accuracy of 0.5% on metered values and 1% on energy and power.
• Systems diagnostic information.
• Breaker health menu.
• Additional protection functions: Undervoltage/overvoltage, Voltage unbalance, Reverse power.

PXR 35

Top-of-the-line trip unit with higher accuracies: 0.25% metering on voltage and current, combining for 0.5% power and energy metering accuracy.

• Improved breaker health algorithm aggregating more data than PXR 20 and PXR 25.
• Integrated Modbus TCP and IEC 61850 (GOOSE) communications.
• Improved ZSI system by allowing trip unit coordination and troubleshooting.
• Review events captured across multiple breakers using PXR 35 with Global Event Capture.
• Additional protective functions: Total harmonic distortion alarm, Phase rotation alarm, Over/under frequency, IEEE curves for long delay.

Zone selective interlocking

The PXR ZSI capability provides positive system coordination without time delays. It allows the breaker closest to the fault to trip first, keeping the rest of the distribution system online, avoiding unnecessary and costly downtime.

Arcflash Reduction Maintenance System

The Arcflash Reduction Maintenance System Maintenance Mode function of the Power Xpert Release trip units reduces arc flash incident energy during a fault condition via a parallel trip circuit that provides fast-acting response. This is separate from normal system protection settings. It operates simultaneously with normal LSIG protection, providing an added backup function. Eaton's system employs a separate, peak-sensing trip circuit that eliminates trip unit microprocessor latencies, resulting in faster clearing times than standard instantaneous tripping. This provides superior arc flash reduction compared to competitor systems that simply lower the instantaneous pickup set point or employ ZSI tripping.

There are three ways to arm the Maintenance Mode setting:

1. Locally: Via a two-position switch on the front of the PXR 20, PXR 25, and PXR 35 trip units. The setting for reduction level is in the SYSTEM submenu.
2. Remotely: Via a remote switch or external relay contact wired through the breaker secondary terminals. Requires a high-quality gold-plated or palladium contact.
3. Via communication device: The trip unit display shows a confirmation screen. A Power Distribution Monitoring and Control-Enhanced or basic display-interface module can be used.

The system has five unique settings (1.5, 2.5, 4.0, 6.0, 10.0 x I) for the pickup of the reduction setting. This prevents inrush currents or load surges from triggering the Maintenance Mode function. PXR trip units can go to a lower setting of 1.5 X the frame rating I for maximum arc flash energy reduction. All three arming methods provide a local indication (blue LED ring around ON/OFF switch) to confirm the Maintenance Mode function. One of the three programmable relays in the frame module can indicate the status. This normally open relay contact allows wiring to an external stack light or annunciator for remote indication.

The Maintenance Mode function provides fast tripping even when the regular Instantaneous is set to OFF. The instantaneous LED position indicates a trip initiated by the Maintenance Mode setting. The LCD display indicates "Maintenance Mode Trip."

Diagram: Arcflash Reduction Maintenance System Time-Current Curve (Figure 20.10-1) illustrating protection curves.

Primary Protection Features

The Time-Current Curves (TCC) for the PXR 20, PXR 25, and PXR 35, when used in Magnum PXR circuit breakers, are found in document TD013172EN. All protection settings must follow the recommendations of the specifying engineer in charge of the installation.

Table 20.10-3. Primary Protection Features

Note: If I²t slope is selected, not all times are available; consult time-current curves. Ground fault pickup is limited to a maximum of 1200 A for ANSI/UL/CSA versions to comply NEC® standards. Maintenance mode pickup maximum setting may be limited based on rating I.

Enhanced Protection Features

Table 20.10-4. Enhanced Protection Features

Note: Three modes of operation are selectable for these protection functions: OFF, Alarm or Trip. Two modes of operation are selectable for these protection functions: OFF or Alarm. Can be mapped to a programmable relay and used in conjunction with the spring release.

Current, Voltage, Frequency, Power and Energy Data

The PXR 20, PXR 25, and PXR 35 provide real-time metering information regarding protected loads. PXR 25 and PXR 35 include monitoring of voltage and phase angle to support power and energy data. All accuracy requires control power (AUX) to the trip unit and is specified for a three-phase balanced load.

Table 20.10-5. Metering Data

Note: Neutral current accuracy for internal sensor (four-pole) breakers. From 50 A to 125 A, current accuracy is ±0.50% of reading and power and energy metering is ±1% of reading; below 50 A, accuracy is ±1% of reading and power and energy metering is ±2% of reading. The PXR 35 includes voltage metering for line and load. By default, the line side is VDB1 (upper terminals) and has 0.25% accuracy. Accuracy for VDB2 (lower terminals) is 1%. Maximum and minimum values are held until reset using PXPM or the display. Demand values are on a configurable fixed or sliding window of 5 to 60 minutes. Power and energy metering and protection functions are calculated with the convention that power flow is from line to load through the circuit breaker. This assumes the top side conductor to be the line side. If the distribution system is configured such that the bottom side is the line side, the power values will indicate reverse power. This can be changed by using the display and navigation button. Navigate to the Edit Settings menu and under Power Feed, select Forward or Reverse.

Magnum PXR Switchgear Class UL 1066 Low-Voltage Power Circuit Breakers

Table 20.10-6. Magnum PXR Switchgear Class UL 1066 Low-Voltage Power Circuit Breakers

Note: Interrupting ratings shown are based on breaker equipped with integral PXR trip unit. Interruption ratings for non-automatic breakers are equal to the published short-time withstand rating. These interruption ratings are based on the standard duty cycle consisting of an open operation, a 15-second interval and a close-open operation, in succession, with delayed tripping in case of short-delay devices. The standard duty cycle for short-time ratings consists of maintaining the rated current for two periods of 0.5 second each, with a 15-second interval of zero current between the two periods. 100 A nominal is only available in narrow frame options. Breaker applied in a tested fan cooled enclosure.

Metering Devices

Power Xpert Energy Meter (PXE)

The PXE offers enhanced accessibility to critical information for managing electrical distribution systems. It supports sag/swell waveform capture and provides real-time circuit information in numeric and graphical formats to monitor circuit parameters (current loading, voltage, power levels, harmonics). Information can be viewed using the optional web-enabled communication module. Optional WiFi offers enhanced connectivity and web browser access.

Image: Power Xpert Energy Meter (PXE) display.

Meter features include:

• ANSI C12.20 0.1 Class and IEC 61000-4-30 Class S revenue meter accuracy.
• 512 samples per cycle waveform capture.
• Fourth CT input to measure neutral current.
• Available in 1A / 5A, and 333 mV CT type inputs.
• Optional 7-inch display.
• Supports a wide range of communication protocols with optional comms module (Modbus TCP/IP, BACnet/IP, EtherNet/IP, IEC 61850, DNP3.0 over IP, MQTT, PROFINET, etc.).
• 8 GB storage with up to 1-second interval data logging.

PXQ

PXQ utilizes aggregated power quality metrics to contextualize disturbance events with adaptable views and personalization. It includes onboard web pages for enhanced root-cause analysis of power quality events.

Image: PXQ power quality meter.

The PXQ series includes:

• Power quality health index.
• Integrated event analysis.
• Sequence of events recording.
• Demand profile and energy usage comparison.
• Multi-channel waveform and graphs.

PXQ Expansion Modules

PXQ provides options for additional capabilities and customization.

Enhanced Capture Module (PXQ-ENH)

Improves PXQ's diagnostic capabilities by detecting and recording high-speed voltage transients (as short as 100 ns with up to 10 kV magnitude). Forensic waveform data is available (1 cycle (17 ms) COMTRADE at 167,000 samples per cycle). When combined with the PXQ-ST2-1A1, it replaces the PXM8000.

Expanded Input Module (PXQ-SER)

Each PXQ can have up to two input expansion modules, each with 16 additional digital inputs, totaling up to 40 inputs (8 + 16 + 16). Digital inputs can be configured for:

• Status monitoring and alerts.
• Sequence of events historian.
• Pulse counting (WAGES).

Image: PXQ system with Enhanced Capture Module (PXQ-ENH) and two Expanded Input Modules (PXQ-SER).

Communications

Power Xpert Gateway 1000

Ethernet communications are available via Power Xpert Gateway PXG1000 with one of three configurations in low-voltage switchgear:

Basic (Gateway)

• Applications are limited to setpoint adjustments and third-party application support.
• Configured to be similar to the PXG900.

Enhanced (Dashboard)

• Configured to provide a collection of views ranging from single-line diagrams to data from devices like meters, relays, and trip units.
• Can be integrated into the switchgear or remotely mounted.
• Requires an HMI to be installed.
• Allows for remote enabling of the Arcflash Reduction Maintenance System via communications.
• Ability to configure setpoints along with remotely opening and closing of circuit breakers.
• Initiate a transfer scheme for uninterrupted power.

Enhanced plus Remote Racking

Includes all options listed above with the addition to control any integral remote racking (MR2) devices installed in the circuit breakers.

Image: Power Xpert Gateway PXG1000 communication module.

Image: Enhanced Graphics Option display showing system overview.

Automatic Transfer

Automatic transfer and intelligent control packages are as follows:

• Eaton ATC-900 controller: Automatic transfer for a two-source lineup with no tie breaker. Additional option for a 7-inch screen available.
• Eaton programmable logic controller (PLC) with Eaton touch screen: Standardized schemes for Main-Main, Main-Gen, Main-Tie-Main, Main-Tie-Gen, and Main-Tie-Tie-Main available. Standardized schemes are supported by Eaton PSC for troubleshooting. Usable with a standard 15-inch Eaton HMI or a PDMC Enhanced platform.
• Eaton Power Systems Control: Offered through Eaton's Engineering Services & Systems. Custom automatic transfers. On-site commissioning. Integration into existing networks.

Image: ATC-900 automatic transfer controller.

Image: Programmable Logic Controller (PLC) module.

For information on automatic transfer and intelligent control solutions, see the LVA Automatic and Intelligent Solutions brochure.

High-Resistance Grounding

General Description

High-resistance grounding adds safety to a grounded system while minimizing service interruptions due to grounds, where continuity of service is a high priority. It provides a path for ground current via a resistance that limits current magnitude, and monitors to determine abnormal conditions. This ensures maximum continuity of service as no tripping occurs for the resistance-limited ground fault. The ground current path is provided at the service beginning by placing resistance in the connection from system neutral to ground. Control equipment continuously measures ground current; a relay detects when current exceeds a predetermined level, alerting personnel. The system has built-in fault tracing. An integral transformer provides control power from the primary source.

Image: Integrated High-Resistance Grounding (HRG) compartment within switchgear.

Standard Features (Basic Version)

• Current sensing ground fault detection (1-5 A pickup/0.5-20 second delay). 1-10 A custom option available.
• Ground current transformer (10/10 ratio).
• Control circuit disconnect switch (fused).
• Lockable door handle.
• Ground current ammeter (0-10 A, 1% accuracy).
• Indicating lights: Red (ground fault), Green (normal), White (pulse).
• Adjustable pulsing timer (0-10 seconds).
• Tapped resistors (1-5 A).
• Three-position selector switch (normal, pulse, test).
• Control switch for manual or automatic reset.
• Ground fault contacts (1NO/1NC).
• Shorting terminal block for ground current transformer.
• UL label.
• Rated for use up to 200 kA fault current system.
• Front accessible.
• Nylon flag type wiremarkers.
• Three "zig-zag" or "wye-broken delta" grounding transformers for systems without a neutral point.

Digital HRG Compartment Features

Standardized digital HRG compartment condenses HRG functionality into a 1/4-high arrangement.

• UL and NEC compliant.
• Utilizes Bender NGRM500.
• Built-in neutral resistor health monitoring.
• Compliant to CSA C22.2 No. 295 requirements.
• Available in 5 A (1-5 A) or 10 A (1-10 A in 2 A increments) tapped resistors.
• Local HMI for programming.
• Accessible through the PXG1000 Enhanced option.

Surge Protection Devices

Integrated SPDs

Eaton integrates industry-leading SPD Series surge protective devices into panelboard and switchboard assemblies. Lead length is minimized to maximize SPD performance. Integrated SPD units are UL listed and labeled to UL 1449 5th Edition.

Image: Eaton SPD-400480Y4C Surge Protective Device.

Key features include:

• Thermally protected metal oxide varistor (MOV) technology.
• 20 kA nominal discharge current (I) rating (maximum rating assigned by UL).
• 50 through 400 kA surge current capacity ratings.
• Three feature package options (basic, standard, and standard with surge counter).
• 200 kA short-circuit current rating (SCCR).
• 10-year warranty.

The breadth of SPD Series' features, options, and configurations ensures the correct unit is available for all electrical applications, including service entrances, distribution switchboards, panelboards, and point-of-use applications. For complete SPD product description, application, and ratings, visit eaton.com/spd.

Power Xpert SPD

The Power Xpert SPD is an advanced monitoring display to track and record surge events and remaining protection status on each phase. Surge events are categorized as low, medium, and high according to IEEE Standard C62.41, logged with time and date stamps. The RJ45 Ethernet port provides communication between the surge device and the LAN connection, Modbus TCP/IP, or BACnet/IP protocols. Ability to access the remote webpage through Power Xpert Gateway 1000. Email alarm notifications are available when configured through Power Xpert Gateway 1000.

Table 20.10-7. Feature Package Comparison

Note: Neutral-ground protection mode available in applicable voltage configurations only.

Layouts and Dimensions

Breaker Layouts

Magnum PXR Rear-Accessible Switchgear

Diagrams illustrating various breaker layouts and structure dimensions for Magnum PXR Rear-Accessible Switchgear.

Main-Tie-Main Example Layouts

Diagrams illustrating various Main-Tie-Main example layouts and dimensions.

Structure Dimensions

Conduit Area Location

Diagrams illustrating structure dimensions and conduit area locations.

Table 20.10-8. Arc-Resistant Structure Dimensions in Inches (mm)

Note: Arc-resistant switchgear's conduit space for bottom entry is the same as regular rear-accessible gear.

Diagrams illustrating structure dimensions, conduit areas, and exhaust configurations.

Heat Loss

Table 20.10-11. Heat Loss Data — Estimated Heat Loss Per Breaker (Watts)

Estimated Heat Loss Per Structure (Watts)

Loss is based on fully loaded vertical and cross bus rating in a structure as given below.

Note: For lower than maximum load currents, watt loss may be estimated by reducing the full load loss by the following: W_L=(I_L/I_FL)²W_FL, where W_L=Load Watts, W_FL=Full Load Watts, I_L=Actual Load Current, I_FL=Full Load Current. Vertical section bus is sized per main cross bus maximum rating or by IEEE C37.20.1 to a maximum of 5000 A. (4000 A in 18.00-inch [457.2 mm] structure.) In addition to the available bus bracings shown in Table 20.10-2, the bus has been tested for short-circuit values of 85 kA for a full 60 cycles.

Closing Times of Magnum PXR Breakers

• 5 cycles or less.

Opening Times—Dependent on Function Used

• Standard instantaneous (per UL 1066): 60 ms+
• Arcflash Reduction Maintenance System trip: 40 ms maximum.
• Shunt trip (per UL 1066): 50 ms maximum.
• Trip signal from an Eaton Arc Flash Relay: ~67 ms.

Center of Gravity

For seismic calculations, the following dimensions should be used to locate the center of gravity for indoor Magnum PXR switchgear.

Table 20.10-12. Center of Gravity Location

Weights

Table 20.10-13. Magnum PXR Indoor Rear Switchgear Structure Approximate Weights (Standard Construction Less Breakers)

Note: See Table 20.10-14 for breaker weights.

Table 20.10-14. Magnum PXR Front-Access Construction Switchgear Structure Approximate Weights (Less Breakers)

Note: See Table 20.10-13 for breaker weights.

Table 20.10-15. Magnum PXR Arc-Resistant Switchgear Additional Approximate Weights

Service Conditions

All low-voltage air power circuit breakers are tested per IEEE Standard C37.1 for a system X/R ratio of 6.6 maximum. It is common within low-voltage systems to experience power factor and X/R values outside the range of standard values, requiring evaluation against published product ratings.

For applications of power breakers within distribution systems having calculated X/R ratios higher than 6.6, derating of the air power breakers kAIC rating is required. Per IEEE methodology, the calculated short circuit current at the point of interest is increased by the Table 20.10-17 multiplying factors (MF) to yield an "apparent value of short circuit current," which is then compared to published breaker ratings. Only breakers with published ratings higher than the "apparent fault current" can be safely applied.

For example, if unfused air power breakers rated 65 kAIC were considered within a 480/277 Vac distribution system where the X/R at the point of breaker application is 14.25 and the calculated fault current was determined to be 60 kA, the determination of the suitability of these breakers yields:

Apparent Fault Current = 60 kA x MF = 60 kA x 1.112 = 66.72 kA

Therefore, because 66.72 kA exceeds the 65 kAIC rating, higher rated kAIC breakers would need to be applied.

Table 20.10-17. Air Power Breaker Derating

Standards

Magnum PXR circuit breakers meet or exceed all applicable requirements of IEEE Standards C37.13 and C37.17, ANSI C37.50 and CSA.

System Voltage and Frequency

Magnum PXR breakers are designed for operation on AC systems only, 60 Hz or 50 Hz, 635 V maximum.

Continuous Current Ratings

Unlike transformers, generators, and motors, circuit breakers are maximum-rated devices with no built-in temporary overload current ratings. Each application must consider maximum anticipated current demand, initial and future, including temporary overloads. The continuous rating of any Magnum circuit breaker with PXR is limited to the frame size current rating. All current ratings are based on a maximum ambient air temperature of 40 °C (104 °F).

Ambient Temperature

The temperature of the air surrounding the enclosure should be within the limits of: -30 °C (-22 °F) to +40 °C (+104 °F).

Altitude

Breakers are applicable at their full voltage and current ratings up to a maximum altitude of 6600 ft (2012 m) above sea level. When installed at higher altitudes, ratings are subject to correction factors in accordance with IEEE C37.20.1.

Table 20.10-16. Altitude Derating Factors

Unusual Environmental and Operating Conditions

Special attention should be given to applications subject to the following conditions:

1. Damaging or hazardous fumes, vapors, etc.: Generally recommended to install switchgear in a clean, dry room with filtered and/or pressurized clean air to avoid derating effects of non-ventilated enclosures.
2. Excessive or abrasive dust.
3. Salt spray, excessive moisture, dripping, etc.: Drip shields in equipment rooms and space heaters in indoor weatherproof enclosures may be indicated depending on severity.
4. Excessively high or low ambient temperatures: For ambient temperatures exceeding 40 °C, continuous current ratings of breaker frame sizes, buses, and current transformers are subject to a derating factor calculated from the formula: (105° Total - Special Ambient, °C) / (105° Total - 40 °C Standard Ambient). Circuit breakers are not adversely affected by very low outdoor ambient temperatures, particularly when energized and carrying load currents. Standard space heaters in weatherproof switchgear raise temperature slightly and prevent condensation. Electrical components like relays and instruments must be applied within manufacturer's specified limits.
5. Exposure to seismic shock: Magnum PXR assemblies and breakers are certified for applications through International Building Code 2021 (IBC) and California Building Code 2019 (CBC). Assembly modifications may be required.
6. Abnormally high frequency of operation: May indicate a lesser number of operations between servicing and more frequent replacement of parts.