YORK YK — VSD - 105% motor current overload

The panel shows exactly VSD - 105% motor current overload; the manual prints no other variant of this text. The message concerns YK chillers running a compressor motor VSD and appears on the OptiView Touchscreen Control Center. The manual lists it in two fault groups: among the variable speed compressor drive cycling fault messages, where it applies to HYP model drives only, and among the variable speed compressor drive safety fault messages, where it applies to all model drives.

The message reports a motor overload. It is generated by the VSD logic board, which monitors the three output phase currents against the chiller FLA value set on that board. When at least one of the three output phase currents stays above 105% of the chiller FLA value for longer than the trip time of the drive, the shutdown is raised: greater than 7 s on TM model drives and greater than 40 s on VSD, LVSD, and HYP model drives. On HYP model drives the same display text is used for the cycling version of the fault, so the message can first appear as a cycling shutdown and then escalate into the safety shutdown described here.

• At least one of the three output phase currents exceeded 105% of the chiller FLA value for greater than 7 s on TM model drives, or greater than 40 s on VSD, LVSD, and HYP model drives — this is the condition under which the VSD logic board generates the safety shutdown on all model drives.
• HYP model drives only: the cycling version of this message is triggered when the VSD logic board detects that at least one of the three output phase currents has exceeded 105% of the chiller's FLA value for greater than 40 s.
• HYP model drives only: the safety shutdown follows when three 105% motor current overload cycling faults occur on any phase within 90 min — the third fault in the 90 min period causes it.

• Trip level: 105% of the chiller FLA value. The chiller FLA value is set by adjustment of the FLA potentiometer on the VSD logic board.
• Trip time to the safety shutdown: greater than 7 s for TM model drives; greater than 40 s for VSD, LVSD, and HYP model drives.
• Trip time of the cycling version on HYP model drives: greater than 40 s above 105% of the chiller's FLA value.
• Escalation on HYP model drives: three cycling faults on any phase within 90 min turn the third fault into a safety shutdown.

After this shutdown, the restart is done at the drive and at the control center. The manual states: In a stopped state, the chiller can be started after the Reset push-button on the VSD logic board is pressed and the Clear button is pressed next to the listed event on the Systems Details screen. For this group of safety faults the manual also notes: Only a qualified service technician must determine the cause and resolution of these conditions.