Eflex 3-5T Precedent & Voyager 2 12.5 - 17.5T with ReliaTel Controls Variable Speed Compressor VFD Troubleshooting

Overview

Eflex 3-5T Precedent & 12.5-17.5T Voyager 2 with ReliaTel controls utilize the same Ruking Variable Frequency Drive (VFD) mounted in the supply fan section of the unit for the control of the variable speed Danfoss compressor. 

In the ReliaTel logic, the variable speed compressor is always Compressor 3, regardless of the amount of installed compressors or unit tonnage. On Voyager 2 units, the variable speed compress is by itself on circuit 2. 

Condenser fans on all Eflex units that utilize ReliaTel controls are ECM motors using a PWM signal. The speed of the condenser fan motor is directly related to the Outdoor Air Temperature (OAT) vs. the running compressor speed. Due to the operation of the condenser fan, no low ambient kit is necessary for low ambient operation and a low ambient kit should ever be fitted to the unit. 

There are only 6 different compressors used on these units in three sizes and to voltages each

• Danfoss VRJ028 used on 3T and 12.5T
• Danfoss VRJ035 used on 4T and 15T
• Danfoss VRJ044 used on 5T and 17.5T

The link below is an internal Elibrary link for the most current version of the Diagnostic Manual for Eflex products. This manual covers both ReliaTel units only for the sizes listed above (Voyager 2 sizes are missing from the cover page, but this is the correct manual). 

Packaged Rooftop Air Conditioners Variable Speed Voyager™ and Precedent™ 3 to 5Tons and 12.5 to 17.5Tons, 60 Hz

Can't access the guide? Contact your local Trane Commercial Sales Office 

DIM Module

The DIM is a remote display for the compressor VFD. The DIM serves multiple functions:

• wired interface between the VSM and VFD
• display current operation of the VFD and display codes
• sets the compressor type for the VFD 

MOD02510 (X13651608010)

Used on 208-230vac and 460vac (on 460vac, only works on DRV01858, X13610009020)

MOD04106

460vac for use with DRV04033 (X13610009040) only

As shown above, there are two DIM modules available. The first MOD02510 works on all 208-230vac drive and 460vac drives with hardware number X13610009020 (NLA). The second DIM shown is a newer version specific to the new 460vac version X13610009040 VFD. These are not interchangeable. 

The DIM has a set of buttons that allow the use to navigate between 5 different menus:

Press SET then UP or DOWN to navigate to each menu

Menu	LED Display	Description
1	1.***	Compressor VFD running frequency.  Example = 41Hz.
2	2.***	N/A
3	3.***	N/A
4	4.***	Drive output current Arms. Example 0-500 means 0-50 Arms
5	5.***	DC bus voltage (value: 0-800 means 0-800 VDC)
6	6.***	Heat sink temp (value: 0-200 means 0 to 200°C)

The resting display will always show F.***, the *** indicates the requested speed input to the DIM. 

Examples:

  = no run command

= requested 60 Hz

The DIM also has a set of dip switches that are used to tell the DIM what compressor is connected. These settings are important and setting them wrong will produce a E-09 error

How does the unit start, stop and control the VFD

When the RTRM determines there is a need for compressor cooling, the VSM will energize the Compressor Run Output (VSM J2-2) which is connected to the VFD Drive Interface Module (DIM) CN101-1. 

At the same time the VSM is starting the VFD, the VSM is also sending the start-up speed command to start ramping up the compressor. This command is passed from VSM J2-5 to DIM CN101-3. This is a 0-10vdc control signal. 

ReliaTel will modulate the compressor speed based on the cooling load required. On startup, shutdown and intervals throughout operation, ReliaTel will ramp the compressor to a fixed speed for 60-90 seconds (depends on where the unit is in operation, ie starting/stopping normal operation) to force oil back to the compressor. If the compressor goes into this oil recovery during normal operation, the compressor speed will return to it's last normal control speed and then begin modulating to maintain the load. 

How does the condenser fan start

When the RTRM determines there is a need for compressor cooling, the VSM will begin sending the PWM (Pulse Width Modulation) signal to the fan motor. This signal alone is what starts the condenser fan motor, there is no relays or contactors involved. This signal can be measured at PPM-VSM using a voltmeter set to DC volts. The range for the condenser fan is ~2-17.5vdc. See condenser fan speed charts below

3-5T

Voyager 2

PWM Vdc values are estimates, actual voltage may vary based on the unit entering voltage and meter accuracy. 

Troubleshooting

Compressor VFD will not start

There a couple of common scenarios where ReliaTel will not start the compressor. This could be due to no actual load request, BAS control, unit is unoccupied and failures. Common failures will be discussed and described below

VSPD Compressor Drive Fault on BAS or TD5 Touchscreen

VSPD Compressor Drive Fault is a generic fault generated by the VSM module based on an alarm input from the DIM CN102-2. This VSM input is monitored and if voltage is detected from the the VFD alarm point, the VSM treats this as a shutdown alarm and will stop all variable speed compressor operation. This is also a manual reset to clear. 

DIM is blank

The DIM is powered by the VFD in the unit. If the DIM does not have power, chances are the VFD also does not have power. The VFD is protected by the Compressor Overload Relay (COVR) that receives high voltage from Compressor Contactor 1 (CC1 Precedent) or Compressor Contactor 3 (CC3 Voyager 2). The COVR is a motor overload block similar to what is found on a motor starter and will trip if the VFD current exceeds the COVR setting. 

On both Precedent and Voyager 2 units, the COVR safety contacts are wired in series with the High Pressure Cutout (HPC) & Discharge Temperature Limit (DTL). If any of these safeties trip, it will drop the control voltage to CC1 (Precedent) or CC3 (Voyager 2) and the control voltage to VSM J2-17 Compressor Proving Input. This will also generate a HPC Disable on the BAS or TD5.    

Precedent 

Voyager 2

In addition to the COVR, between the COVR and CC1 on Precedent and ahead of CC3 on Voyager 2, are fuses FU24/25/26. 

Precedent

Voyager 2

After the COVR, both Precedent and Voyager 2 utilize a Power Factor Correction Module (PFC). This module is a capacitor bank that is used to "clean" the power entering the VFD. It is not uncommon to see a ~10vac increase in voltage across the PFC, this is normal. This is typically not an issue, but on 460v units where the incoming power to the unit is already pushing the max of 506vac, the VFD could start to attempt protect itself as it will start seeing power in the 510-520vac range. The correct course of action would be to discuss with the customer and their utility provider. 

The output of the PFC is typically very consistent phase to phase  and phase to ground. Any PFC with a phase imbalance of more than 2% phase to phase should be replaced. 

Error code: - Communication Failure

Criteria - Loss of communication between the DIM and the VFD. 

Troubleshooting - Verify the wiring connections between the DIM and the VFD.

Reset Criteria - The protection will remain active for at least 2 minutes. If the issue clear on it's own, after 2 minutes, protection mode will be deactivated when communication is re-established between interface board and the inverter module.

Error code: - Hardware Overcurrent Limit

Criteria - Output current of the VFD is higher than the specified limit for hardware over-current protection. During normal operation mode, the drive output current should not reach this value.

Troubleshooting - Verify there are no loose connections in input power wiring to the VFD and output wiring from the VFD to the compressor. Check compressor windings for any ground faults. Check for abnormal conditions such as airflow blockage, improper condenser fan operation, compressor locked rotor situation, system charge or other conditions that could cause the system to be overloaded.

Reset Criteria - The protection will remain active for at least 2 minutes. After 2 minutes, protection mode will be
deactivated and drive will operate normally as long as the overload condition is no longer present. Drive 

Warning Code: & Error Code: - Software Overcurrent

Criteria - Output current of the drive is higher than the specified limit for software over-current protection.

Over-current limits associated with P-01 code are lower than the limits associated with E-05. During P-01, the
compressor speed is either reduced or held constant whereas during E-05, the compressor is requested to shut
down to protect the drive. 

During normal operation mode, the drive output current should not reach the limits associated with E-05.

Troubleshooting - Verify there are no loose connections in input power wiring to the drive and output wiring from the electric drive to the compressor. Check compressor windings for any ground faults. 

Check for abnormal conditions such as airflow blockage, improper condenser fan operation, compressor locked rotor situation, system charge or other conditions that could cause the system to be overloaded. 

Reset Criteria - The protection or error code will remain active for at least 2 minutes. After 2 minutes, protection or error mode will be deactivated and drive will operate normally as long as the overload conditions are no longer present.

Error Code: - DC Bus Over Voltage and Under Voltage

Criteria - DC bus voltage of the drive is above or below the specified limits for the drive. The DC Bus voltage can be checked on the DIM module, see instructions at the top of the article. 

• 230 Vac Drive limits: Above 370 Vdc or below 170 Vdc
• 460 Vac Drive limits: Above 800 Vdc or below 300 Vdc

Troubleshooting - Verify input voltage to the R, S, T terminals on the inverter module is within +/-10% of the rated unit voltage. Inspect DC bus board for any damaged capacitors.

Reset Criteria - The protection will remain active for at least
2 minutes regardless of DC bus voltage. After 2 minutes,
protection mode will be deactivated when DC bus voltage is
below or above the specified limits for the drive.

Error Code: - Incorrect Compressor Code

Criteria - Interface module sends the compressor code that is not supported by the inverter module.

Troubleshooting - Verify dip switch settings on the interface module are set correctly for appropriate compressor
model and re-apply power to the drive. On older units, turn power off and cycle the dip switches and return them to their original locations. If this corrects E-09, replace the DIM. 

Reset Criteria - Error mode can be de-activated by removing power to the drive board and re-applying power

Error Code: - AC Input Power Phase-Loss

Criteria - Loss of any of three phases of AC input power for longer than 30 m sec when the drive has been powered for at least 6 sec.

Troubleshooting - Verify all three phases of AC input power to the R, S, T terminals on the inverter module. 

Reset Criteria - The protection will remain active for at least 2 minutes. After 2 minutes, protection mode will be deactivated and drive will operate normally.