| Document type | Service Information Letter |
|---|---|
| Document number | SI0401 |
| Equipment | YMC2 Magnetic Bearing Centrifugal Chiller |
| Brand | YORK |
| File size | 0.5 MB |
Fault codes in this document
OUTPUT LINE VOLTAGE ISOLATION BOARD SYMPTOMS
| Code / display | Meaning | Cause | Action | Page |
|---|---|---|---|---|
| High Phase (A B or C) Motor Current | High motor current at 4 seconds into run. | If one of the transformers has failed it can provide incorrect values to the VSD logic board, causing the VSD logic board to incorrectly control the VSD. | Check the condition of the three fuses supplying the board regardless of the fault experienced; if the output line voltage isolation board is suspected, the primary and secondary windings can be checked (Tables 1–4). | 1 |
| MBC – Speed Signal Fault | Cycling shutdown set when the MBC loses the speed signal that is expected from the VSD, or the speed signal is less than 10 Hz, while the MBC is commanded in Rotation Mode. | If the output line voltage isolation board transformer phase A has failed, this fault will occur. | The MBC Fault contacts open. The MBC remains in Levitation mode with the motor shaft levitated until commanded to de-levitate over the serial communication line. The shutdown is released when the MBC is out of Rotation mode or speed greater than 10 Hz is transmitted. A 10 second bypass exists when the initial command to Rotation Mode occurs. | 1 |
| WARNING – VSD – DC Bus Active | Warning displayed anytime the DC bus voltage is greater than 50 volts and the drive is not in the run state. | If 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. There are multiple conditions that could generate this message. | Work on this equipment should only be done by properly trained personnel who are qualified to work on this type of equipment. 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 (Tables 1–4). | 1 |
| VSD – DC Bus Lockout – Do Not Cycle Power | Shutdown generated anytime the bus voltage should be zero, but it is greater than the threshold level based on the drive software version: 50 VDC before March of 2014 with software of C.HYP.03.02.02, C.HYP.04.02.02 and earlier; 100 VDC after March of 2014 with software of C.HYP.03.03.01, C.HYP.04.03.01 and later. | There are multiple conditions that could generate this message; if related to the output line voltage isolation board, the source could be the same as for WARNING – VSD – DC Bus Active (damaged transformer winding insulation with respect to ground allowing current flow to ground and a differential voltage between the positive and negative bus). | Do not cycle power. 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 (Tables 1–4). | 2 |
| Incorrect Voltage Values on the VSD Details Screen | Incorrect values shown on the VSD details screen. Phase A output voltage signal is used for the speed reference; Phase B and C are displayed for reference on the VSD details screen but they do not impact the drive operation. All phases of output voltage should be balanced. | If phase B or C transformers were to fail, the result would be incorrect values on the VSD details screen but the machine could still operate. There are multiple conditions that could generate this message in addition to the output line voltage isolation board. | Refer to the drive service manual for assistance in determining the source of the issue. 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 (Tables 1–4). | 2 |
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