YORK YK — VSD - Single phase input power

The control center display reads VSD - Single phase input power. It is one of the variable speed drive cycling fault messages for YK centrifugal liquid chillers, appearing in both the medium voltage variable speed drive list and the variable speed compressor drive list.

The VSD monitors the RMS value of each of the three phase line-to-line input voltages on a cycle-by-cycle basis. If the RMS voltage of any of the three inputs drops below 75% of the drive's nameplate voltage rating — that is, below the low limit for the drive model in any half cycle — the drive initiates this cycling shutdown.

For all model drives, this shutdown is generated by the SCR trigger control and relayed to the VSD logic board to initiate a system shutdown. For HYP model drives, the voltage measurement and the fault detection are all done by the VSD logic board.

• The RMS value of any one of the three line-to-line input voltages falls below the low limit for the drive model — below 75% of the drive's nameplate voltage rating — in any half cycle.

• General shutdown point: RMS voltage of any input below 75% of the drive's nameplate voltage rating.
• Input line voltage 400 VAC to 460 VAC, TM/VSD drive: low limit 230 VAC.
• Input line voltage 575 VAC, TM/VSD drive: low limit 300 VAC.
• Input line voltage 380 VAC or 415 VAC, HYP drive: low limit 264 VAC.
• Input line voltage 460 VAC, HYP drive: low limit 295 VAC.

This fault is a cycling shutdown with automatic recovery, and no separate reset procedure is described. Messages automatically clear when the fault condition no longer exists; if the chiller was running when the fault occurred, it automatically restarts.