On the display
At the panel the message reads Motor or starter - Current imbalance. The manuals also print it as Motor or Starter - Current Imbalance. In one software version this text is listed as a former safety shutdown message, combined into Motor or Starter - Output Current Imbalance, so on that software the same trip is reported under the combined wording. On a chiller with an LCSSS, the same fault appears in the liquid cooled solid states starter safety fault messages list under the heading LCSSS - Motor or starter - Current imbalance.
What it means
This is a safety shutdown: the 3-phase compressor motor current imbalance was greater than 30% continuously for 45 s. The LVSSS and VSD detect the unbalance condition and advise the OptiView Control Center Microboard through the serial communications. The shutdown is not performed on electromechanical starter applications. On a chiller with an LCSSS, the fault is set by the LCSSS trigger/logic board, and the calculation is the same as the OptiView uses.
Why it appears
- The 3-phase compressor motor current imbalance exceeded 30% and stayed above that level continuously for 45 s.
What to check
- Confirm the chiller had been running for at least 45 s — the imbalance check is not performed before that point.
- Confirm the average of the three phases of motor current was greater than 80% of the programmed 100% chiller FLA — below that average the check is not performed either.
- Confirm the starter is not electromechanical — on electromechanical starter applications this safety shutdown is not performed.
Setpoints and thresholds
- Imbalance trip level: greater than 30%.
- Imbalance duration: continuously for 45 s.
- Run-time arming: the check is not performed until the chiller has been running for at least 45 s.
- Current arming: the check is not performed until the average of the three phases of motor current is greater than 80% of the programmed 100% chiller FLA.
Reset and restart
The fault is released only from a stopped chiller. The manual's instruction: The fault is released when the chiller is in a stopped state and the Clear button is pressed next to the listed event on the Systems Details Screen.
Questions engineers ask
What does Motor or starter - Current imbalance mean on a YORK YK?
It is a safety shutdown that means the 3-phase compressor motor current imbalance was greater than 30% continuously for 45 s. The LVSSS and VSD detect the unbalance condition and advise the OptiView Control Center Microboard through the serial communications.
How do I clear the current imbalance fault on a YORK YK?
The chiller must be in a stopped state. Then press the Clear button next to the listed event on the Systems Details Screen to release the fault.
At what imbalance does a YORK YK trip on motor current?
The trip level is an imbalance greater than 30%, held continuously for 45 s. The check is not performed until the chiller has been running at least 45 s and the average of the three phases of motor current is greater than 80% of the programmed 100% chiller FLA.
Why does my YK display Motor or Starter - Output Current Imbalance instead?
In one software version, Motor or Starter - Current Imbalance is listed as the former safety shutdown name, combined into Motor or Starter - Output Current Imbalance. It is the same protection under that software's wording.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YK; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YK messages: fault codes · YORK YK documentation · YORK manuals