Digital Acoustics ESBx-110 Dokumentacja Pobierz pdf (Strona 327)

Maintenance and Troubleshooting

ADDvantage-32 PLUS ● AC to DC Power Converter

7-29

7.6 TEST PROCEDURE FOR LEAKING THYRISTORS/SCRs

An SCR might be leaky or shorted if a false Tach Loss and/or SCR SHRTX + fault

occurs when the DC contactor closes. To determine this, perform the following steps:

1. From the main keyboard/display menu, use the up and down arrow keys

until “OPERATE” is displayed.

2. Press the right arrow key and “DRIVE ANALOG” will be displayed.

3. Press the right arrow key again and “A000 FIL SPEED” will be displayed.

4. Press the up arrow key until “A012 ARM VOLTS” is displayed. Verify

that the section is stopped and the DC contactor is open. If the voltage is

above 10 or 20 volts, an SCR may be leaking. If an SCR is shorted

significantly, the drive diagnostics should fault out on power up. The

FAULT FIFO should indicate which SCR is bad.

The diagnostics may indicate a shorted SCR at drive power up that may actually be the

leaking SCR; it may be identified as follows:

SCR SHRT A+ CR1 SCR SHRT A- CR4

SCR SHRT B+ CR2 SCR SHRT B- CR5

SCR SHRT C+ CR3 SCR SHRT C- CR6

On the other hand, the fault diagnostics may not be able to reliably determine exactly

which SCR is leaking. For a leaking SCR, the fault diagnostics are clearable and the drive

will run without blowing the 3-phase line fuses. A shorted SCR will cause one or two

3-phase line fuses to blow. The following test should be done to make sure FAULT

FIFO has correctly identified the shorted SCR or to identify a leaky SCR.

1. Power off the drive.

2. Open the drive to access the Bridge Interface board.

3. Disconnect all the removable connectors on the board and swing open the panel to

expose the snubber board.

4. Disconnect the snubber board by removing the connector P1 on the snubber

board. However, for large drives this may not be possible. Therefore, skip this

step for drives 540 amperes and above.

5. Clip a lead from a DVM to SCR bus A1 (BA1) located on main base assembly.

6. Reconnect all cables on bridge interface board.

7. Power up drive (run off). Measure and record AC volts between BA1 and

Phase A, Phase B, Phase C.

8. Turn power off to drive. Move clip lead from bus bar A1 to bus bar A2 (BA2) by

first removing all the cables on the bridge interface board.

9. Reconnect cables on the Bridge interface board.

10. Power up drive with run off. Measure and record the AC volts between bus bar

A2 and Phase A, Phase B, Phase C.

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Digital Acoustics ESBx-110 Dokumentacja Strona 327