Phase Reversal Protection Lost Diagnostic

Issue:

Phase Reversal Protection Lost Diagnostic

Resolution:

RTAA, RTWA, RTUA Chillers:

See RTAA-SVB10B-EN for reference/troubleshooting this problem.

Other causes:  CTs, Wiring (Power and Control), Connections (Power and Control), Compressor Module.

• Use RTAA-SB-9 or RLC-SVD03A-EN for troubleshooting of the Current Transformers (CTs).
• Verify wiring tightness and correct polarity on the CTs.
• Look for interference on the incoming power from DC motors, VFDs, etc.

Use tests in RTAA-SVB10B-EN click here

Miscellaneous Testing:

• Phase unbalance diagnostic is generated when a 15% unbalance condition has been detected.  The technician will want to use his amp meter and monitor the three phase power and compare the current of each leg.  If the current measured on the amp probe does not exceed 15%, the incoming power is OK and the Current Transformers (CT's) should be checked out as well as the continuity from the CT's to the compressor module for that circuit.  The possibility of a bad compressor module also exists.
• Use the current transformer section troubleshooting bulletin (RLC-SVD03A-EN), step 9 to check the integrity of the module input.  You could also swap positions of the 1U4 and the 1U5 to see if the problem follows the module to the other circuit.  The switches on the modules will need to be changed to match how they are currently set before swapping.  These are switch 1 and switch 2.  Switch 1 is the IPC address and is unique for each module.  Switch 2 is the compressor overload switch.  If the size of compressors is the same on each circuit, this switch will not need to be changed, however, if the compressors are different sizes, Switch 2 will need to be changed to reflect the correct CT scale setting. 

•  If needed, install a recorder to monitor voltage/current variations from the power utility.

• Try swapping the leads from A to B, B to C, and C to A. If the problem follows the lead than it is in the incoming power.  If it stays with the compressor winding than it is in the compressor motor.

• The machine has a 15% trip point that will call out Current Unbalance.  This can be disabled without fear of damaging the compressor as there is a non-defeatable 30% severe unbalance protection that will still be active.  If the chiller trips on the severe phase unbalance, then a recorder needs to be installed to determine if there are some incoming power problems.

Notes:

See RLC-SVD03A-EN (70-125 TON chillers) or RTAA-SB-5 (130-400 TON chillers) for additional reference.

Notes:

Changes:

Other Question/Problem/Cause Statements:

• Phase Reversal Protection Lost Diagnostic
• How do I troubleshoot the current transformers
• CT checkout procedure

Facts:

• Air-Cooled Chiller (Pueblo) (RTAA 130-400 Ton)
• Air-Cooled Chiller (Pueblo) (RTAA 70-125 Ton)

Combined the Following HUB Documents : DOC-80744 and DOC-85873