19XRV with PIC 6 Controls Danfoss VLT FC102

SAFETY CONSIDERATIONS

DANGER Failure to follow these procedures will result in severe personal injury or death. ONLY QUALIFIED electrical personnel familiar with the construction and operation of this equipment and the hazards involved should install, adjust, operate, or service this equipment. READ AND UNDERSTAND this manual and other applicable manuals in their entirety before proceeding. Failure to observe this precaution could result in severe bodily injury or loss of life. DO NOT install modification kits with power applied to the drive. Disconnect and lock out incoming power before attempting such installation or removal. Failure to observe this precaution could result in severe bodily injury or loss of life. UNUSED WIRES in conduit must be grounded at both ends to avoid a possible shock hazard caused by induced voltages. Also, if a drive sharing a conduit is being serviced or installed, all drives using this conduit should be disabled to eliminate the possible shock hazard from cross-coupled motor leads. Failure to observe these precautions could result in bodily injury. DO NOT VENT refrigerant relief valves within a building. Outlet from rupture disc, relief valve or any other type of safety relief device must be vented outdoors in accordance with the latest edition of ANSI/ASHRAE 15 (American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers). The accumulation of refrigerant in an enclosed space can displace oxygen and cause asphyxiation. PROVIDE adequate ventilation in accordance with ANSI/ ASHRAE 15, especially for enclosed and low overhead spaces. Inhalation of high concentrations of vapor is harmful and may cause heart irregularities, unconsciousness, or death. Misuse can be fatal. Vapor is heavier than air and reduces the amount of oxygen available for breathing. Product causes eye and skin irritation. Decomposition products are hazardous. DO NOT USE OXYGEN to purge lines or to pressurize a chiller for any purpose. Oxygen gas reacts violently with oil, grease, and other common substances. NEVER EXCEED specified test pressures. VERIFY the allowable test pressure by checking the instruction literature and the design pressures on the equipment nameplate. DO NOT USE air for leak testing. Use only refrigerant or dry nitrogen. DO NOT VALVE OFF any safety device. BE SURE that all pressure relief devices are properly installed and functioning before operating any chiller. THERE IS A RISK OF INJURY OR DEATH by electrocution. High voltage may be present on the motor leads even though the motor is not running. Open the power supply disconnect before touching motor leads or terminals.

DANGER Failure to follow these procedures may result in personal injury or death. DO NOT work on high-voltage equipment unless you are a qualified electrician. DO NOT WORK ON electrical components, including control panels, switches, VFD, or oil heater until you are sure ALL POWER IS OFF and no residual voltage can leak from capacitors or solid-state components. LOCK OPEN AND TAG electrical circuits during servicing. IF WORK IS INTERRUPTED, confirm that all circuits are de-energized before resuming work. AVOID SPILLING liquid refrigerant on skin or getting it into the eyes. USE SAFETY GOGGLES. Wash any spills from the skin with soap and water. If liquid refrigerant enters the eyes, IMMEDIATELY FLUSH EYES with water and consult a physician.

WARNING DO NOT USE TORCH to remove any component. System contains oil and refrigerant under pressure. To remove a component, wear protective gloves and goggles and proceed as follows: a. Shut off electrical power to unit. b. Recover refrigerant to relieve all pressure from system using both high-pressure and low pressure ports. c. Traces of vapor should be displaced with nitrogen and the work area should be well ventilated. Refrigerant in contact with an open flame produces toxic gases. d. Cut component connection tubing with tubing cutter and remove component from unit. Use a pan to catch any oil that may come out of the lines and as a gage for how much oil to add to the system. e. Carefully un-sweat remaining tubing stubs when necessary. Oil can ignite when exposed to torch flame. Failure to follow these procedures may result in personal injury or death.

WARNING DO NOT ATTEMPT TO REMOVE fittings, covers, etc., while chiller is under pressure or while chiller is running. Be sure pressure is at 0 psig (0 kPa) before breaking any refrigerant connection.

CAUTION USE only repair or replacement parts that meet the code requirements of the original equipment. PERIODICALLY INSPECT all valves, fittings, and piping for corrosion, rust, leaks, or damage. DO NOT re-use compressor oil or any oil that has been exposed to the atmosphere. Dispose of oil per local codes and regulations. DO NOT leave refrigerant system open to air any longer than the actual time required to service the equipment. Seal circuits being serviced and charge with dry nitrogen to prevent oil contamination when timely repairs cannot be completed.

CAUTION Failure to follow these procedures may result in personal injury or damage to equipment. TO AVOID an electric shock hazard, verify that the voltage on the bus capacitors has discharged completely before servicing. Check the DC bus voltage at the power terminal block by measuring between the +DC and -DC terminals, between the +DC terminal and the chassis, and between the -DC terminal and the chassis. The voltage must be zero for all 3 measurements. THE USER is responsible to conform with all applicable local, national, and international codes. Failure to observe this precaution could result in damage to, or destruction of, the equipment. THIS DRIVE contains ESD (electrostatic discharge) sensitive parts and assemblies. Static control precautions are required when installing, testing, servicing or repairing this assembly. Component damage may result if ESD control procedures are not followed. Typical ESD protections are ESD mat and grounded wrist strap. DO NOT alter the setting of any jumper. Failure to observe this precaution could result in damage to, or destruction of, the equipment. USE OF power correction capacitors on the output of the drive can result in erratic operation of the motor, nuisance tripping, and/or permanent damage to the drive. Remove power correction capacitors before proceeding. Failure to observe this precaution could result in damage to, or destruction of, the equipment. MOST CODES require that upstream branch circuit protection be provided to protect input power wiring. DO NOT route signal and control wiring with power wiring in the same conduit. This can cause interference with drive operation. Failure to observe this precaution could result in damage to, or destruction of, the equipment. DISTRIBUTION SYSTEM short circuit capacity shall not exceed the rating of the drive. Failure to observe this precaution could result in damage to, or destruction of, the equipment. DO NOT STEP on refrigerant lines. Broken lines can whip about and release refrigerant, causing personal injury. DO NOT climb over a chiller. Use platform, catwalk, or staging. Follow safe practices when using ladders. USE MECHANICAL EQUIPMENT (crane, hoist, etc.) to lift or move inspection covers or other heavy components. Even if components are light, use mechanical equipment when there is a risk of slipping or losing your balance. BE AWARE that certain automatic start arrangements CAN ENGAGE THE VFD, TOWER FAN, OR PUMPS. Open the disconnect ahead of the VFD, tower fans, or pumps.

INTRODUCTION

The Carrier VFD option Start-Up and Service Manual is intended for trained and qualified service personnel and is to be used during start-up, operation, and maintenance of Danfoss VLT FC102 series drives.

ABBREVIATIONS AND EXPLANATIONS

Frequently used abbreviations in this manual include:

• DC -- Direct Current
• HMI -- Human Machine Interface
• IGBT -- Insulated Gate Bipolar Transistor
• I/O -- Inputs/Outputs
• IP -- Internet Protocol
• LCP -- Local Control Panel
• LEN -- Local Equipment Network
• MCB -- Main Control Board
• MDCIC -- Multi-Drive Control Interface
• MOV -- Metal Oxide Varistor
• PCB -- Printed Circuit Board
• PE -- Protective Earthing Conductor
• PIC -- Product Integrated Control
• PWM -- Pulse Width Modulation
• STO -- Safe Torque Off
• VFD -- Variable Frequency Drive

Required Publications

The Carrier VFD option Start-Up and Service Manual must be used with the following manuals:

• Latest version of the Danfoss VLT FC 102 and VLT parallel AC Drives manuals as applicable.
• Latest revision of the Start-Up, Operation, and Maintenance Instructions for the 19XR with PIC 6 Controls.
• Latest revision of the Controls Operation and Troubleshooting manual for 19XR with PIC 6 Controls.

Getting Assistance from Danfoss

For technical support on drives, contact Technical Support experts: 1-888-Danfoss (1-888-326-3677).

Before calling, have the following information available. Type Code and Serial Number can be found on the Danfoss data nameplate. See Fig. 1.

• Danfoss nameplate including: Carrier VFD Code (Carrier Part Number), Danfoss Part Number / Type Code (T/C), Danfoss Serial Number (S/N)
• Images of cable connections, filters, resisters, fuses, chokes, etc.
• Alarms/warnings experienced
• MCT 10 *.ssp file

For detailed repair procedures, refer to Danfoss VLT Drive Service Manual MG94A502.

IDENTIFYING DRIVE COMPONENTS

Chiller control, VFD Power Assembly and VFD schematics are included in Appendix A.

WARNING DC bus capacitors retain hazardous voltages after input power has been disconnected. After disconnecting input power, wait the time specified in Table 1 or as specified on the Danfoss VFD nameplate for the DC bus capacitors to discharge. Always check the voltage with a voltmeter rated for the DC bus voltage to ensure the DC bus capacitors are discharged before touching any internal components. For parallel drive modules (N630 and larger) check voltage before and after the individual DC fuses. Failure to observe these precautions could result in severe bodily injury or loss of life.

An isolated multimeter with diode tester is needed to measure DC bus voltage and to make resistance and diode checks.

Capacitor Discharge Time

The Danfoss VFD offering has a passive rectifier section and a six pulse inverter section. For Danfoss VFD frames DD and DE, chiller topology offering consists of a VFD power panel and a separate Danfoss drive mounted on the chiller condenser. The VFD power panel contains the required integration components for the VFD to operate with the chiller system. These components consist of the main circuit breaker, oil pump breaker and terminal block feed to power panel, terminal blocks, control power circuit breaker, control transformers, heater power terminal block feed, and fan relays.

The larger Danfoss DP frame size is used for multiple power modules to be used in parallel. The drive modules and the VFD power panel components are consolidated into a common enclosure.

The Danfoss VFD offering includes optional protective MOVs for VFD electrical surge protection and volt- and ammeter options along with a line reactor offering. The drive is offered with no local control panel (LCP) keypad, and therefore if programming is required, a version of Danfoss' MCT-10 will need to be installed on a laptop. For details of MCT-10, see Danfoss published literature VLT1 Motion Control Tools MCT 10 Setup Software Operating Instructions. Note that a keypad is required for some service functions such as enabling LEN on a non-Carrier configured Danfoss type code. (LEN is configured default on a Carrier type code.) A keypad is also required if a drive power card is being replaced.

WARNING Electrical shock can cause personal injury and death. Shut off all power to this equipment during installation. There may be more than one disconnect switch. Tag all disconnect locations to alert others not to restore power until work is completed. Refer to Fig. 2 for lockout/tagout details.

When there is a need to access the VFD enclosure to do any troubleshooting, it is important to identify the type of drive prior to initiating any work.

The Carrier FC-102 Danfoss product offering consists of three main configurations: D size, E size, and D size parallel drive (PD) modules. See details for the D size drive in Fig. 3, for the E size drive in Fig. 4, and for the D size parallel drive modules in Fig. 5. The product range covers a drive range of 315 to 1000 kW. When any work or troubleshooting is required, it is critical to determine the type of drive since their design layouts vary. This can be done by locating the Carrier VFD label located on the outside of the drive or the Danfoss type code on the Danfoss VFD nameplate and matching up the appropriate VFD Power Rating in Table 2 or Table 3.

VFD Type by Frame Size, D-E

VFD Type by Frame Size, PD

NOTE: Weight and dimensions for PD (parallel drive) for the Danfoss power module are for the combined VFD enclosure (both VFD and VFD power panel components).

Rigging

D, E SIZES Drive enclosure and associated components are heavy. To avoid injury be sure to use appropriate equipment with appropriate weight ratings for lifting. Always use dedicated lifting eyes for lifting and never walk under suspended load. Wear PPE such as gloves, safety glasses and safety shoes to prevent injury. Ensure correct length of lifting cables so lifting angle is 65 degrees or larger with horizontal (Fig. 6). Always use lifting eye bolts (Fig. 7) to rig drive if it needs to be removed from the chiller. Note that E series drives are placed on the chiller in horizontal position and will need to be rigged from that orientation using rigging eyes in the four corners.

PARALLEL DRIVE MODULES

Parallel Drive Modules consist of four smaller D size modules installed in parallel configuration.

Install eye bolts and rig individual modules as a D series drive. Note that some component removal is necessary to gain access to remove an individual drive.

If the entire drive module enclosure is to be rigged, use dedicated rigging lugs. Use the 4 rigging lugs located in each corner of the drive enclosure.

The PD enclosure can be lifted by the 4 outside eyebolts. Lifting angle must never be more than a 45 degree pull (Fig. 8). See Fig. 9 for location of eyebolts.

Components and Physical Data

19XRV Carrier Danfoss VFD Part Numbers are structured as shown in Fig. 10 and 11.

D Size Drive

The D size FC-102 drive and Carrier VFD control panel are positioned side by side off-center on top of the condenser shell. Both the drive and the VFD control are positioned on a common base on the condenser.

The Carrier VFD power panel is where the customer runs unit incoming power; the panel contains all required components to interface with the VFD, control panel, and power panel. See Fig. 12-14.

NOTE: ITEMS PRECEDED BY AN ASTERISK (*) ARE OPTIONS.

To check DC bus voltage, check voltage between terminal 1 and 2 as depicted below. To reach the DC bus location, a voltmeter with safety probe tip extenders must be utilized since the DC bus studs are located far back in the drive. See Fig. 15 and static checks later in this manual.

E Size Drive

The E size FC102 drives have higher amperage capacity compared to the D size. Like the D size, the E size drive is positioned on the condenser in conjunction with the VFD power panel. The E size drives are mounted in horizontal position. The E size drives are mounted on a VFD bracket arrangement supported and suspended between the condenser tubesheets. See Fig. 16.

For the smaller D size drives, customer incoming power is terminated in the VFD Power Panel; power leads are run from the VFD Power Panel to the VFD and from the VFD to the motor (see Fig. 17). The main power panel is detailed in Fig. 18. For an interior view of the E drive enclosure, see Fig. 19; Fig. 20 details control shelf elements.

For static checks, an isolated multimeter with diode tester is needed to measure DC bus voltage and to make diode checks. DC+ and DC- terminals are identified in Fig. 21 for E sized drives.

D and E Size VFD Power Panel Schematics

See Fig. 22 and 23 for detailed drawings.

LEGEND

• ACR -- Analog Control Relay
• ALM -- Alarm
• ALMR -- Alarm Relay
• AUX -- Auxiliary
• COMP -- Compressor Motor
• CR -- Control Relay
• CT -- Control Transformer
• DS -- Door Switch
• FL -- Fluorescent Lamp
• FU -- Fuse
• J -- Jumper
• LR -- Line Reactor
• LS -- Limit Switch
• MCB -- Master Circuit Breaker
• MCB, SH -- Master Circuit Breaker, Shunt Trip
• NC -- Normally Closed
• NO -- Normally Open
• SCB -- Service Circuit Breaker
• SCB, SH -- Service Circuit Breaker, Shunt Trip
• SOL -- Solenoid
• SPD -- Surge Protective Device
• ST -- Shunt Trip
• TB -- Terminal Block
• V -- Voltmeter
• VFD -- Variable Frequency Drive
• BLK -- Color Black
• RED -- Color Red
• YEL-GRN -- Color Yellow-Green

PD Size Drive

PARALLEL DRIVE SYSTEMS - DP1120 - DP1670 Parallel drive (PD) systems consist of four D size FC-102 drives mounted in a common enclosure, creating a larger PD size with greater ampacity than D and E size drives. As per Table 3 the Carrier PD size drives offering yields a range up to 1670 amp.

NOTE: INSTALL CARRIER-PROVIDED TOPHAT TO ALLOW FOR ADEQUATE SPACE FOR INCOMING POWER CABLES.

The PD size drive enclosure includes both the drive components and the VFD Power Panel components which were separated in its own enclosure for the D and E drive size offering. See Fig. 24-26.

NOTE: Enclosure does not represent Carrier application.

Control Shelf

The control shelf contains the MDCIC (multi-drive control interface card), and control card. The MDCIC is connected to each of the drive modules via a ribbon cable and communicates to the control card. The control card controls the operation of the drive modules. See Fig. 27.

PD Module

Each drive module has an IP00 protection rating. Four modules are connected in parallel to create a drive system. See Fig. 28-29.

The parallel drive modules contain 2 DC fuses per drive module.

DC Bus

When testing parallel drive systems do the following:

• To access the DC bus voltage, use the REGEN terminals at the top of one of the modules.
• When testing DC bus voltage for the entire system, it is not necessary to remove the interlink connections between the individual drives.
• When testing DC bus voltage for an individual drive, the module must be isolated by removing interlink connections and the control cable connections of the module.

For DC bus location, see Fig. 30. For more details, see the PD VFD module wiring schematic (Fig. 31).

START-UP

DANGER Internal components and circuit boards of the drive are live when the drive is connected to incoming power. Coming into contact with this voltage is extremely dangerous and will result in severe personal injury or death. The motor terminals U, V, W and the DC bus (DC+ and DC-) are live when the drive is connected to incoming power, even if the motor is not running. Do not make any connections when the drive is connected to the incoming power. After having disconnected the drive, if any service work is to be performed wait for the capacitors to fully discharge. The minimum waiting time is specified on the drive label. Prior to performing any repair work measure DC bus voltage with a volt meter. For drives in parallel ensure to measure DC bus voltage before and after the individual DC fuses. Before connecting the drive to the incoming power, make sure that the enclosure is closed.

WARNING The control I/O-terminals are isolated from the mains potential. However, the relay outputs and other I/O terminals may have a dangerous control voltage present even when the drive is disconnected from incoming power. Coming into contact with this voltage could result in severe personal injury.

Alternate Wire Lugs

If the incoming power wire size in the VFD power panel does not fit the standard lug, alternate lugs may be available. Please contact the circuit breaker manufacturer for availability. Note that lugs rated for a higher current than the circuit breaker may be used. See Table 4 for wire lug specifications.

Verify Installation

Record the following job information:

1. Job Name
2. Job Number
3. City
4. State
5. Zip Code

Record the following nameplate information; it is suggested to take a picture of the appropriate nameplates for future reference.

1. From the Danfoss nameplate (Fig. 1) located inside the VFD enclosure:
   • Danfoss Type Code (TC) Number
   • Danfoss Serial Number
2. From the machine nameplate (Fig. 32) located on the VFD enclosure:
   • Chiller Serial Number
   • Chiller Model
   • Motor rated load amps
   • Motor nameplate rpm
   • Motor nameplate kW
   • Motor nameplate voltage
   • Voltage

Grounding bar hole size:

• DD/DE size: 14 mm (0.55 in.)
• PD size: 18 mm (0.71 in.)

Configure the VFD

All configurations required by the VFD are supplied by the HMI through the VFD Gateway. The Danfoss Std Tier VFD can operate with PIC 6 via LEN. Any configuration changes necessary and possible are made on the HMI screens. A complete set of configurations is transmitted to the VFD each time the controls are powered up.

Table 5 shows parameters in the Unit Mounted VFD Configuration menu for PIC6. Parameters in italics are to be entered or confirmed at start-up.

Commissioning the Unit

The commission procedure is as follows:

1. If the chiller has been stored outdoors, allow at least 24 hours room temperature stabilization prior to commissioning. Ensure any condensation that occurs as a result of the ambient temperature is allowed to evaporate.
2. Verify parameters in the VFD_CONF UM VFD Config (CFGUMVFD) screen against chiller nameplate.
3. Install surge suppression devices if required.
4. Review the power wiring and grounding to ensure that it has been properly connected.
5. Visually examine the inside of the drive enclosure to:
   • Look for signs of corrosion or moisture residue.
   • Remove any dirt or debris.
   • Make sure all vents are clear.
6. Apply power to the drive and take thermal measurements of the capacitor bank and power connections. Do this again before start-up.
7. Measure and record the incoming line voltage. Line-to-line voltages should be balanced within 3% as calculated below:

   Measure voltages phase-to-phase and phase-to-ground.

   Vmax = Maximum measured phase-to-phase voltage (A to B, B to C, C to A)

   Vmin = Minimum measured phase-to-phase voltage

   Vavg = (VAB + VBC + VCA) / 3

   Imbalance % = ((Vmax - Vmin) / Vavg) x 100

8. Take a final thermal measurement of the capacitor bank and power after finalizing the installation to ensure all connections are good.
9. If a ground fault occurs, then do the following:
   • Check for a ground in the motor or motor wiring.
   • Check for damage to wiring insulation and that wiring is dry.
   • Verify the motor wiring is separated from ground and there is no connection between phases.
   • Check for failed IGBTs.
10. If an overcurrent fault occurs, then do the following:
    • Check for excessive load and verify load limit settings on the HMI.
    • Check motor and wiring insulation.
    • Check parameter settings in Table 5.

SERVICE

WARNING DC bus capacitors retain hazardous voltages after input power has been disconnected. After disconnecting input power, wait the time specified in Table 1 or as specified on the Danfoss VFD nameplate. For the DC bus capacitors to discharge and then check the voltage with a voltmeter rated for the DC bus voltage to ensure the DC bus capacitors are discharged before touching any internal components. For parallel drive modules (N630 and larger) check voltage before and after the individual DC fuses. Failure to observe this precaution could result in severe bodily injury or loss of life.

An isolated multimeter with diode tester will be needed to measure DC bus voltage and to make resistance and SCR/ IGBT checks.

Troubleshooting the Drive

An isolated multimeter with diode tester is needed to measure DC bus voltage and to make resistance and diode checks.

The drive can display two (2) kinds of error codes on the PIC6 HMI called Alert and Alarm codes. These codes signal a problem detected during self-tuning or drive operation.

• A warning message on the HMI is an ALERT. The same message when viewed with Danfoss' software MCT-10 is a VFD WARNING.
• A failure resulting in a shutdown is seen as an ALARM on the HMI and the VFD when viewed with Danfoss' software MCT-10.

CONDITION CODES

• CHILLER ALERT = VFD WARNING
• CHILLER ALARM = VFD ALARM

See Tables 5 and 6.

CHILLER ALERT CODES

An alert condition is indicated by a message on the HMI screen. The drive will continue to operate during the alert condition. Investigate the cause of the alert to ensure it does not lead to a fault condition. The alert code will automatically be cleared from the HMI when the condition causing the alert no longer exists. See the 19XR Controls Operation and Troubleshooting manual for PIC6 controls.

CHILLER ALARM CODES

An alarm condition is also indicated by a message on the HMI screen. If an alarm occurs, the drive coasts to stop. For the drive to restart, the underlying condition must be resolved and the drive must be Reset. This can typically be done from the PIC6 HMI by resetting the Alarm. In rare instances, the reset may need to be done with Danfoss MCT-10 software or a customer-supplied LCP (Local Control Panel). See the 19XRV Controls Operation and Troubleshooting manual for PIC6 controls for chiller Alarm codes.

TEST EQUIPMENT NEEDED TO TROUBLESHOOT

An isolated multimeter adequately rated for DC bus voltage will be needed to measure DC bus voltage and make resistance checks. Note that dedicated troubleshooting test points are not provided.

VISUAL INSPECTION FAULT TROUBLESHOOTING

When troubleshooting a unit which has been in service for an extended period of time, do not assume that everything external to the drive is fine. Look for issues such as loose connections, improper programming. It is suggested to look at all the following:

• Cable routing; check for parallel routing of wires.
• Control wiring; check for broken or damaged wires and connections. In parallel drive systems, check connections between the control shelf and the modules. Check the voltage source of the signals.
• Cooling; check operation of all cooling fans. Check the enclosure filters. Check for blocked air passages. Check the positive and negative interconnections between modules.
• DC fuse micro-switch; In parallel drive systems, check that the micro-switches have been snapped properly onto the DC fuse fixtures.
• DC fuse mounting; In parallel drive systems, check both ends of DC fuses for loose connections.
• Interior; check that the drive is free of dirt, metal chips, moisture, and corrosion. Check for burnt or damaged power components, or carbon deposits resulting from component failure. Check for cracks in the housings of power semiconductors, or for pieces of broken component housings inside the unit.
• Environmental; The drive can operate within a maximum ambient temperature of 50°C (122°F) and a 24-hour temperature limit of 45°C (113°F). Humidity levels must be less than 95% non-condensing. Check for harmful airborne contaminants such as sulfur-based compounds.
• Grounding; The drive requires a dedicated ground wire from its enclosure to the building ground. Grounding the motor to the drive enclosure is recommended. Check that ground connections are tight and free of oxidation.
• Input power wiring; Check for loose connections, proper fusing, and blown fuses.
• Motor; Check the nameplate ratings of the motor. Ensure that the motor ratings correspond with the drive ratings. Check that the motor parameters (parameter 1-20 Motor Power [kW] to parameter 1-25 Motor Nominal Speed) are set according to the motor ratings. It is sufficient to check these values from the PIC6 configuration menu.
• Output to motor wiring; Check for loose connections. Check for switching components in the output circuit. Check for faulty contacts in the switchgear. In parallel drive systems, check for proper interconnections between the modules. Check cable length and cross-section imbalance between the terminals of the modules. One missing wire can cause an overcurrent trip.
• Programming; Make sure that drive parameter settings are correct according to motor, application, I/O configuration.
• Proper clearance; Drives require adequate top and bottom clearance to ensure proper airflow for cooling. Ensure that no foreign elements are obstructing air flow.
• Vibration; Look for unusual amounts of vibration around the drive.

VERIFY THAT DC BUS CAPACITORS ARE DISCHARGED

The drive's DC bus capacitors retain hazardous voltages after input power has been disconnected. Perform the following steps before touching any internal components:

1. Turn off and lock out input power. Wait the appropriate time as indicated on drive nameplate.
2. Verify that there is no voltage at the drive's input power terminals.
3. Measure the DC bus potential with a voltmeter while standing on a non-conductive surface and wearing insulated gloves (1000 V). Measure the DC bus potential. The voltage between DC+ and DC-, and from each DC terminal to the chassis must be zero before proceeding. For parallel drive modules, measure for DC-bus voltage before and after the individual DC fuses.
4. Once the drive has been serviced, reapply input power.

Checking Power Modules and Motor Input with Input Power Off -- Static Test

Use the following procedure to check the drive's power module circuitry with power off:

1. Turn off and lock out input power. Wait appropriate time as per Danfoss VFD nameplate.
2. Verify there is no voltage at the drive's input power terminals.
3. Using a voltmeter, check the DC bus potential as described in the section Verifying That DC Bus Capacitors Are Discharged to ensure the DC bus capacitors are discharged.
4. Disconnect the motor from the drive.
5. Check all AC line and DC bus fuses.
6. Use a multimeter to perform a static check on the input diodes and output IGBTs. See Table 7. For parallel drives, this test will have to be done for each individual drive module, so in addition to removing the input and motor busbars for parallel drives, the DC link connection will have to be removed for the individual drives.
7. Check motor impedance.
8. Reconnect the motor to the drive.
9. Reapply input power.

WARNING DC bus capacitors retain hazardous voltages after input power has been disconnected. After disconnecting input power, wait the time specified in Table 1 or as specified on the Danfoss VFD nameplate. For the DC bus capacitors to discharge and then check the voltage with a voltmeter rated for the DC bus voltage to ensure the DC bus capacitors are discharged before touching any internal components. For parallel drive modules (N630 and larger) check voltage before and after the individual DC fuses. Failure to observe this precaution could result in severe bodily injury or loss of life.

An isolated multimeter will be needed to measure DC bus voltage and to make resistance checks.

Digital meters require a special diode check function because the current sourced by the meter during a normal resistance (Ohms) test is too low to accurately test a diode. Make sure the meter is set to the diode test function. Voltage readings may not be exact as shown in the above table, but look for consistency during each of the 4 tests. When performing a test that should return infinity (OL) as shown in the above table, you should see a value slowly climbing toward infinity. This is a result of the meter charging a capacitor and is normal.

If an incorrect reading is observed associated with U, V, W (outputs), this indicates a failed inverter IGBT module. Replace the shorted IGBT modules. Similarly, if an incorrect reading is observed associated with R, S, T (inputs), this indicates a shorted SCR. Replace the shorted SCR module.

Servicing the Drive

WARNING To guard against possible personal injury and/or equipment damage:

1. Inspect all lifting hardware for proper attachment before lifting drive.
2. Do not allow any part of the drive or lifting mechanism to make contact with electrically charged conductors or components.
3. Do not subject the drive to high rates of acceleration or deceleration while transporting to the mounting location or when lifting.

WARNING DC bus capacitors retain hazardous voltages after input power has been disconnected. After disconnecting input power, wait the time specified in Table 1 or as specified on the Danfoss VFD nameplate. For the DC bus capacitors to discharge and then check the voltage with a voltmeter rated for the DC bus voltage to ensure the DC bus capacitors are discharged before touching any internal components. For parallel drive modules (N630 and larger) check voltage before and after the individual DC fuses. Failure to observe this precaution could result in severe bodily injury or loss of life.

An isolated multimeter will be needed to measure DC bus voltage and to make resistance checks.

Refer to Fig. 33 for location of DC bus terminals.

For FC-102 service guide lines, refer to Danfoss Manuals; the latest Service Guide for VLT FC Series is MG94A502.

Troubleshooting Fault Codes

Table 6 provides descriptions and corrective actions for typical Danfoss alarm/warning codes and their corresponding PIC6 alarm codes.

NOTE: This is not a complete list of Danfoss FC-102 codes. If a warning/alarm is present which is not included in this table refer to the Danfoss manual.

APPENDIX A -- WIRING SCHEMATICS

This section contains wiring schematics for the 19XRV Chiller Control (PIC 6), and the 19XRV Compressor Power Panel.