YORK YMC2 — VSD - PRECHARGE - LOW DC BUS VOLTAGE 2

The panel prints VSD - PRECHARGE - LOW DC BUS VOLTAGE 2. The manuals list it among the cycling shutdown messages of the YMC2's VSD.

During Pre-charge the VSD watches the DC bus voltage against a threshold that follows the Line Voltage Setpoint. One manual requires the DC-link voltage to climb to the high threshold fixed by the Line Voltage Setpoint — 500 V at a 460 V setpoint, 414 V at 380/415 V, 250 V at 230 V — no later than 15 seconds after the pre-charge command is given. The other manual phrases it as the DC Bus voltage having to exceed the minimum threshold set by the Line Voltage Setpoint — 414 V for 380/415 V and 500 V for 460 V — within 12 seconds of that signal. If the voltage has not got there in time, the VSD generates this shutdown.

• The DC bus voltage failed to come up to the pre-charge threshold that the Line Voltage Setpoint determines within the time window after the pre-charge signal was commanded — one manual allows 15 seconds, the other 12.

• Line Voltage Setpoint 460 V — threshold 500 V
• Line Voltage Setpoint 380/415 V — threshold 414 V
• Line Voltage Setpoint 230 V — threshold 250 V (this row appears in one manual; the other lists only the 380/415 V and 460 V rows)
• Time allowed after the pre-charge signal — 15 seconds in one manual, 12 seconds in the other

Recovery from this fault is automatic. The logic board of the VSD times 10 seconds, then clears the fault and lets another pre-charge attempt start; the VFD's fan(s) and water pump(s) stay energized through that wait. The board tolerates three pre-charge-related faults in a row — once the third occurs, it raises the Safety Shutdown message VSD - PRECHARGE LOCKOUT.