On the display
The control center shows WARNING - VSD - DC Bus Active. The manual prints the message in this form only, with no variants. It is listed as a warning, and the manual discusses it under the output line voltage isolation board symptoms.
What it means
Per the manual, this warning is displayed anytime the DC bus voltage is greater than 50 volts and the drive is not in the run state. Read it as: voltage above 50 volts is present on the VSD DC bus while the drive is not running.
Why it appears
- The manual states that there are multiple conditions that could generate this message.
- If the warning is related to the output line voltage isolation board, the transformer winding insulation with respect to ground is damaged: current will flow to ground and can cause a differential voltage to appear between the positive and negative bus.
- The magnitude of the voltage on the bus is dependent on the impedance with respect to ground.
What to check
- Confirm who does the work:
Work on this equipment should only be done by properly trained personnel who are qualified to work on this type of equipment.
The manual warns that failure to comply could expose the worker, the equipment and the building and its inhabitants to the risk of injury or property damage. - Check the condition of the three fuses supplying the board.
- If the output line voltage isolation board is suspected, the primary and secondary windings can be checked; the manual refers to Tables 1-4 for these winding checks.
Setpoints and thresholds
- DC bus voltage threshold: the warning condition is a bus voltage greater than 50 volts.
- Drive state: the second condition is that the drive is not in the run state.
Questions engineers ask
What does WARNING - VSD - DC Bus Active mean on a YORK YMC2?
It is displayed anytime the DC bus voltage is greater than 50 volts and the drive is not in the run state — in other words, voltage is present on the DC bus while the drive is not running.
What causes the DC Bus Active warning on a YMC2 chiller?
The manual lists multiple conditions that could generate the message. If it is related to the output line voltage isolation board, damaged transformer winding insulation with respect to ground lets current flow to ground and can create a differential voltage between the positive and negative bus.
What should I check when WARNING - VSD - DC Bus Active appears?
Check the condition of the three fuses supplying the board, and if the output line voltage isolation board is suspected, its primary and secondary windings can be checked (Tables 1-4). Only properly trained personnel qualified to work on this type of equipment should do the work.
Is it safe to work on the drive with this warning active?
The warning means the DC bus voltage is greater than 50 volts. The manual states that work on this equipment should only be done by properly trained personnel who are qualified to work on this type of equipment.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YMC2; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YMC2 messages: fault codes · YORK YMC2 documentation · YORK manuals