AUTOMATIC TRANSFER SWITCHES
for Industrial Power Systems
YOUR JOB IS COMPLEX. WE MAKE IT EASY.
This document introduces Kohler's Automatic Transfer Switches (ATS) for industrial power systems, highlighting their integration, reliability, and ease of use. Unlike typical ATS units, Kohler's integrated power systems are built around quality transfer switches designed and manufactured by Kohler to meet specific power requirements.
Beyond the hardware, Kohler provides a dedicated team of engineers focusing on every system element—generator, transfer switch, switchgear, and controller—to ensure the system precisely meets user needs. Projects are supported by an expert team, customized to exact requirements, delivered on budget, and on time, from specification to startup and service.
TOTAL SYSTEM INTEGRATION
Kohler offers a fully integrated system approach, connecting various components for seamless operation:
Diagram Description: A schematic illustrates a building connected to utility power and two Kohler generators. The system components shown are: 1. KOHLER GENERATOR (Gas generators 40–1300 kW, Diesel generators 10–4000 kW), 2. KOHLER AUTOMATIC TRANSFER SWITCH (supporting open, closed, and programmed transition operating modes; available in standard, bypass-isolation, and service-entrance configurations), 3. KOHLER REMOTE ANNUNCIATOR (for remote monitoring and testing of transfer switches), 4. KOHLER PARALLELING SWITCHGEAR (for low and medium voltage applications), 5. KOHLER DECISION-MAKER® CONTROLLER (controls, monitors, and aids system diagnostics), and 6. KOHLER MONITORING SOFTWARE (monitors generators and transfer switches from a PC).
THE ATS LINEUP
Peace of mind starts here.
Kohler Automatic Transfer Switches (ATS) bridge the gap between utility and standby power, distributing power to critical loads. Each ATS requires a controller for seamless power transfer; Kohler's Decision-Maker® MPAC® controllers offer versatile options for matching function to application.
STANDARD FEATURES
- Multiple Applications: Available in standard, bypass-isolation, and service-entrance configurations with open, closed, and programmed transition operating modes, ranging from 30 to 4000 amps.
- Seamless System Integration: Designed to interface perfectly with Kohler generators and paralleling switchgear.
- Advanced Communications: Equipped with Ethernet and Modbus communication capabilities.
- Certified Packages: UL-listed with CSA and IBC certifications available.
AUTOMATIC TRANSFER SWITCHES
They protect your power. And your business.
Diagram Description: Images showcase three types of ATS configurations: Standard ATS (a single cabinet), Service-Entrance ATS (a cabinet with a prominent disconnect), and Bypass-Isolation ATS (a larger cabinet, with an internal view detailing its components). Key features include:
- 1. Certified Enclosures: Meet NEMA Type 1, 3R, 12, 4, and 4X standards.
- 2. Bypass Operation: Eliminates load interruption during maintenance.
- 3. Decision-Maker® Controller: Offers advanced features including communications, I/O, and load management.
- 4. Heavy-Duty Contactor: Available with specific breaker, time-based, or current-limiting fuse-rated mechanisms.
- 5. Available Accessories: Include anticondensation heaters, voltage-surge suppressors, and seismic certification.
CUSTOM-CONFIGURATIONS
The chart tells the story.
Kohler allows users to custom-configure switches by selecting exact components, enabling the provision of the correct switch for any application with efficient delivery. Each letter and numeral in the model number corresponds to a specific ATS element. An example model, KBP-DMVA-0150S, is detailed.
Configuration Example: KBP-DMVA-0150S breakdown:
- K: Model (Kohler)
- B: Bypass-isolation mechanism
- P: Programmed transition
- D: Decision-Maker® MPAC® 1500 controller
- V: 4-pole, 4-wire with switched neutral
- A: NEMA 1 enclosure
- 0150: Rated at 150 amps
- S: Standard connection
The document provides detailed tables for selecting Mechanism, Transition, Controls, Voltage, Poles/Wires, Enclosure, Amps, Connection, Utility (KEP), and Generator (KEP) options.
| MECHANISM | Transition | Controls | Voltage | Poles/Wires |
|---|---|---|---|---|
| S - Standard (Specific Breaker) | S - Standard | A - MPAC 1200 | C - 208 V / 60 Hz | T - 3-Pole / 4-Wire, Solid Neutral |
| C - Standard (Time Based) | P - Programmed | D - MPAC 1500 | D - 220 V / 50 Hz | N - 2-Pole / 3-Wire, Solid Neutral |
| B - Mechanically Operated Bypass-Isolation | C - Closed | B - MPAC 1200 Nonautomatic | F - 240 V / 60 Hz | V - 4-Pole / 4-Wire, Switched Neutral |
| A - Electrically Operated Bypass-Isolation | F - MPAC 1500 Nonautomatic | G - 380 V / 50 Hz | W - 4-Pole / 4-Wire, Overlapping Neutral | |
| E - Service Entrance | H - 400 V / 50 Hz | |||
| J - 416 V / 50 Hz | ||||
| K - 440 V / 60 Hz | ||||
| M - 480 V / 60 Hz | ||||
| N - 600 V / 60 Hz | ||||
| P - 380 V / 60 Hz | ||||
| R - 220 V / 60 Hz | ||||
| S - 400 V / 60 Hz |
| ENCLOSURE | Amps | Connection | Utility (KEP) | Generator (KEP) |
|---|---|---|---|---|
| A - NEMA 1 | 30–4000 | S - Standard | M - MCCB TM 100–200 A | K - MCSW 100–1200 A |
| B - NEMA 12 | F - Front | N - MCCB ET 250–800 A | M - MCCB TM 100–200 A | |
| C - NEMA 3R | P - MCCB ET GF 1000–1200 A | N - MCCB ET 250–1200 A | ||
| D - NEMA 4 | R - ICCB ET 800 A | Q - ICSW 800–4000 A | ||
| F - NEMA 4X | T - ICCB ET GF 1000–4000 A | R - ICCB ET 800–4000 A | ||
| G - OPEN |
MCCB = Molded-Case Circuit Breaker, ICCB = Insulated-Case Circuit Breaker, MCSW = Molded-Case Switch, ICSW = Insulated-Case Switch, TM = Thermal-Magnetic Trip Unit, ET = Electronic Trip Unit
MECHANISM TYPES
Options for every application.
Kohler offers three primary mechanism types for automatic transfer switches:
- Standard Transfer Switch: Features a single mechanism for transferring load between power sources. Available in standard/open, delayed/programmed, and closed transition modes.
- Bypass-Isolation Transfer Switch: Combines an automatic and a manual transfer switch into one unit. Essential for critical applications like hospitals and data centers where power interruption for maintenance is not an option. It allows servicing of the ATS while maintaining power to the facility via the manual switch. Available with mechanically or electrically operated bypass.
- Service Entrance Transfer Switch: Functions as both the ATS and the utility disconnect, utilizing circuit breakers and motor operators. The utility source breaker serves as the main entrance point, and the emergency/generator source disconnect can be a breaker or switch. Available in delayed/programmed transition.
ENCLOSURE RATINGS
Protect your property.
NEMA ratings, developed by the National Electrical Manufacturers Association, define enclosure standards for industrial environments, specifying protection against weather, water, dust, and light. The appropriate NEMA rating should be chosen based on the installation location.
- NEMA 1 (General purpose): For indoor use under normal conditions; protects against dust, light, and indirect water splashing; prevents contact with live electrical parts.
- NEMA 3R (Weather-resistant): For indoor or outdoor use; provides protection against falling rain and ice formation; meets tests for inadvertent access, external icing, and rust resistance.
- NEMA 4 and 4X (Watertight and weatherproof): For indoor or outdoor use; protects against splashing and hose-directed water; constructed of corrosion-resistant material (4=steel, 4X=stainless steel).
- NEMA 12 (General purpose): For indoor use; protects against circulating particles and dripping of noncorrosive liquids; meets drip-, dust-, and rust-resistant tests.
TRANSITION TYPES
Factory-configured for mode of operation.
The transfer switch controller manages power sensing, timing, and fault monitoring for automatic operation. Switches can be configured in one of three modes:
- Standard/Open Transition (Break Before Make): The load is disconnected from one source before connecting to the alternate source. This is common for loads that are not highly inductive or mission-critical. The load is disconnected from power during transfer.
- Delayed/Programmed Transition (Break Both Sides): Used for highly inductive loads like motors and transformers. The load disconnects from one source, pauses in an "off" position to allow magnetic field decay, and then connects to the alternate source, protecting against power surges. Load is disconnected during all transfers. Delay time is user-programmable.
- Closed Transition (Make Before Break): Used in mission-critical applications where momentary load interruption is unacceptable. Sources overlap, providing power simultaneously, and synchronize before transfer. The load is never disconnected when both services are available. Transfers to open transition if one source fails or fails to sync. Features an external fail-safe timer.
Diagram Descriptions:
- Standard/Open Transition: Illustrates power flow from utility and generator to a switch, showing the load being disconnected from one source before connecting to the other.
- Delayed/Programmed Transition: Depicts a sequence where the load is disconnected, pauses in an "off" state, and then reconnects to the alternate source.
- Closed Transition: Shows a scenario where both utility and generator power sources are momentarily connected in parallel before the switchover is complete.
CONTROLLERS
Three options. Endless solutions.
The Decision-Maker® Automatic Transfer Switch Controllers are the "brain" of the ATS, dictating its operational logic.
- MPAC 1200: A customizable solution offering full control of system behavior, including extended I/O for specific applications.
- MPAC 1500: Ideal for managing loads, prime power applications, or three-source systems, providing backup for backups.
Controller Comparison Table:
| DECISION-MAKER | MPAC 1200 | MPAC 1500 |
|---|---|---|
| Amperage | Up to 4000 | Up to 4000 |
| Phases | Single/Three | Single/Three |
| Poles | 2, 3, 4 | 2, 3, 4 |
| Voltage Range | 115–600 | 115–600 |
| Product Type | ||
| Standard Open Transition | Yes | Yes |
| Standard Delayed Transition | Yes | Yes |
| Standard Closed Transition | Yes | Yes |
| Bypass-Isolation Open Transition | Yes | Yes |
| Bypass-Isolation Delayed Transition | Yes | |
| Bypass-Isolation Closed Transition | Yes | |
| Service Entrance | Yes | Yes |
The document further details user interface features, voltage and frequency settings, time delays, configuration settings, communications, and accessories for both MPAC 1200 and MPAC 1500 controllers.
POLES AND NEUTRAL SWITCHING
Ground-fault protection without compromise.
Selecting between a solid or switched neutral is crucial when specifying an ATS. A 2-pole/3-pole ATS uses a solid, unswitched neutral, while a 4-pole ATS features a fully rated switched neutral that follows the contactor position. Neutral switching can be open or overlapping (closed).
The choice between 2-pole/3-pole or 4-pole transfer switches, and the required neutral switching type, is determined by the emergency system grounding and ground-fault protection method, as specified by National Electrical Code (NEC) and National Fire Protection Association (NFPA) regulations.
- Solid Neutral: Typically for 2-pole or 3-pole configurations. Features constant contact and the generator is not a separately derived source.
- Switched Neutral: For 4-pole configurations. Features break-before-make on neutral, switching neutral with phase contacts, and the generator is a separately derived source.
- Overlapping Neutral: For 4-pole configurations. Features make-before-break on neutral, with the neutral contact momentarily tied between two sources during switching. The generator is a separately derived source.
Diagram Descriptions:
- Two-Pole/Three-Pole Transfer Switches: Illustrates a system where the neutral connection is not dependent on switch position. A ground fault is sensed at the switchgear, and the current returns to the generator via the system neutral.
- Four-Pole Transfer Switches: Depicts a system requiring a 4-pole switch for generator ground fault sensor detection. The generator is a separately derived source with a neutral-to-ground link. A ground fault returns to the generator's neutral-to-ground bond, tripping the generator breaker.
WITHSTAND AND CLOSE-ON RATING
Ensure the reliability of your ATS.
Withstand and Close-On Rating (WCR) measures an ATS's ability to withstand fault (short circuit) current for a specific period and to close into a fault while continuing to operate. The required WCR is determined by the electrical system's short-circuit study and upstream protective device trip times.
Choosing the correct WCR is vital; an unnecessarily high rating leads to overspecification and expense, while an insufficient rating can cause significant damage.
- Specific Breaker: Series-rated ATS tested in coordination with specific upstream circuit breakers. Offers higher WCR ratings but limits breaker choice.
- Time-Based ("Any breaker"): ATS tested to withstand faults for a set duration (e.g., 3 cycles), allowing use with any UL 489 circuit breaker. Offers flexibility.
- Current-Limiting Fuse: Limits fault current, protecting downstream components. Fuses require replacement after a fault event.
Diagram Description: A diagram illustrates a typical power distribution setup including a Main CB, a Transfer Switch, Distribution CB, Generator CB, and Loads, showing the flow of power and potential fault paths.
Short-Time Rating: This rating is for selective coordination, requiring longer fault current duration. It represents the lowest WCR level among the four rating types.
THE KOHLER DIFFERENCE
Simple solutions to complex problems.
THREE-SOURCE SYSTEM: BACKUP TO YOUR BACKUP
This system offers redundancy without the complexity of paralleling systems. Available with the MPAC® 1500 controller, it uses two generators and two ATS units. The first ATS determines utility or generator power, and the second ATS identifies which generator is active. This provides automatic backup power and extends generator runtime and refueling intervals.
Diagram Description: A schematic shows utility power and two generators feeding into two ATS units, which then supply power to loads, illustrating a redundant backup configuration.
THE BENEFITS ARE MANY:
- One generator is available when the other is being serviced.
- Automatic backup power from the second generator is available for critical applications.
- Alternating generator runtime extends time between maintenance and overhauls.
- Lengthens time between refueling due to two fuel sources.
- Provides peace of mind, as one generator failure is covered by the other.
MANAGING LOADS
Power critical loads at all times.
To maintain system stability and prevent generator shutdown due to exceeding output capacity, Kohler offers methods to manage loads:
- LOAD SHED: Allows a programmed transition to transfer loads to an "off" position, removing them from the generator. Primarily for lower-priority loads. Requires a load-shed module.
- LOAD CONTROL: Allows up to nine individual loads to be added or removed.
- TIME-BASED LOAD CONTROL: Adds or removes loads based on pretransfer and posttransfer events. Useful for starting multiple motors sequentially to avoid overwhelming the generator. Requires I/O modules.
- CURRENT-BASED LOAD CONTROL: Adds or removes loads based on real-time current measurements. If output capacity is insufficient, low-priority loads are removed. Requires a current-sensing kit and I/O modules.
TRANSFER SWITCH ACCESSORIES
Add function and flexibility.
Kohler transfer switch accessories enhance customization for specific facility needs:
- INPUT-OUTPUT (I/O) MODULES:
- Programmable Standard I/O Module: Two programmable inputs, six programmable outputs.
- Programmable High-Voltage/Current I/O Module: Two programmable inputs, three programmable outputs.
- Programmable Alarm Module: Provides a 90-dB alarm horn and programmable annunciation for preferred source, supervised transfer control, and Chicago alarms.
- External Battery Supply Module (EBSM): Powers the controller during generator startup, essential for three-source systems.
- Anticondensation Heater: Prevents humidity issues within enclosures.
- Controller Disconnect Switch: Safely removes power from the controller for servicing.
- Current-Sensing Kit: Monitors current in each line, displayed on the LCD interface.
- Digital Meter Kit: Provides an LED display for voltage, amperage, frequency, power, and other metrics.
Additional accessories include:
- Generator Connection Box: Enables quick, safe generator connection; rated at 600 VAC or less, with NEMA 3R enclosure.
- Line-to-Neutral Voltage Monitor: Standard on four-pole switches and certain KCS switches.
- Load-Shed Module: Allows load transfer to the off position via an external contact closure.
- Monitor III Communications Program: Displays status and control of ATS on a PC.
- Engine Start Circuit Monitoring System: Monitors the integrity of the start circuit wiring between ATS and generator.
- Remote Annunciator: For remote monitoring and testing of up to four transfer switches.
- Supervised Transfer Switch: A key-operated three-position selector (auto-manual-transfer).
- Surge Protective Devices (SPD): 100-kA surge suppressor with LED indication.
- User Interface Cover: Hinged and lockable cover for door-mounted interfaces.
SERVICE AND SUPPORT
The help you need. Any time, anywhere.
Kohler provides extensive global service and support through over 800 locations worldwide. These locations offer sales, installation, and aftermarket support services, with expertise in power specifications, equipment, and integration. Kohler Power professionals are available 24/7 for troubleshooting, advice, service, and support.
Global Presence:
- KOHLER: Headquarters and Manufacturing in Kohler, Wisconsin; Headquarters EMEA; Headquarters Asia Pacific and Manufacturing in Singapore; Manufacturing Facilities in India and China.
- SDMO (KOHLER-OWNED): Headquarters and Manufacturing Facilities in France; Manufacturing Facility in Brazil.
Sales Offices, Dealers, and Distributors are located globally.
Contact Information:
- North America: 800.544.2444
- Website: KOHLERPOWER.COM
Printed in U.S.A. © 2021 BY KOHLER CO.
