On the display
The control center shows VSD - DC bus pre-regulation. The manual lists it among the variable speed compressor drive cycling fault messages, and this exact wording is the only variant it prints for this chiller. The entry applies to all model drives.
What it means
The drive has entered the pre-regulation state, but the DC bus voltage has not increased to a value of ±50 V of the DC bus voltage setpoint within 2 s. The setpoint is not one fixed number: it depends on the rated input voltage of the VSD and on the rated motor voltage. Because the bus voltage does not come into that window in time, the shutdown is generated.
Why it appears
- The DC bus voltage has not risen to within ±50 V of the DC bus voltage setpoint within 2 s after the drive entered the pre-regulation state; the setpoint follows from the rated input voltage of the VSD and the rated motor voltage (the manual names no other cause for this shutdown).
Setpoints and thresholds
- Shutdown window: the DC bus voltage must reach a value of ±50 V of the DC bus voltage setpoint within 2 s after entering the pre-regulation state.
- HYP model pre-regulation DC bus threshold — rated input voltage 380 to 415 with rated motor voltage 380 to 460: DC bus pre-regulation setpoint 680.
- Rated input voltage 460 with rated motor voltage 380 to 460: DC bus pre-regulation setpoint 750.
- Rated input voltage 380 to 460 with rated motor voltage 575: DC bus pre-regulation setpoint 820.
Reset and restart
The manual gives no manual reset step for this message; recovery is by automatic retry. After a delay of 10 s, the VSD attempts another pre-charge and pre-regulation cycle.
If this shutdown occurs three consecutive times, the chiller locks out on a VSD - DC bus pre-regulation lockout.
Questions engineers ask
What does VSD - DC bus pre-regulation mean on a YORK YK chiller?
The VSD entered the pre-regulation state, but the DC bus voltage did not rise to within ±50 V of the DC bus voltage setpoint within 2 s, so the drive generates this shutdown. The setpoint depends on the rated input voltage of the VSD and the rated motor voltage.
What is the DC bus pre-regulation setpoint for a YK VSD?
For HYP model drives the manual lists a setpoint of 680 for rated input voltage 380 to 415 with rated motor voltage 380 to 460, 750 for 460 input with 380 to 460 motor, and 820 for 380 to 460 input with 575 motor.
Why does the YK show VSD - DC bus pre-regulation again after a while?
After a 10 s delay the VSD automatically attempts another pre-charge and pre-regulation cycle. If the shutdown occurs three consecutive times, the chiller locks out on a VSD - DC bus pre-regulation lockout.
How do I clear VSD - DC bus pre-regulation on a YORK YK?
The manual describes no manual reset for this message. The VSD waits 10 s and then attempts another pre-charge and pre-regulation cycle on its own; three consecutive shutdowns end in a VSD - DC bus pre-regulation lockout.
Messages next to this one
The same message on other models
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