8-6
Transformer
Inspect the transformer as described below.
1. Check the external appearance
2. Retighten the bolts of transformer I/O terminals and primary voltage tap terminals
3. Measure the transformer secondary voltage.
Turn on the control power supply and medium-voltage power supply, and measure the input voltages to the
power cells as shown in Fig. 8.2.
Measure the input voltage of each power cell by using a digital multimeter AC range. (Measure the input
voltage across L1, L2, L3 of each power cell.) The measured input voltage must be the rated voltage (630
VA C ) ±10 V. If the majority of measured values exceeds the allowable range, adjust the primary voltage
tap (+10, +5, or 0% can be selected).
Power Cells
Inspect all the power cells as described below.
1. Check the external appearance.
Check for discoloration indicating burn marks, for leakage from the smoothing capacitor, and for protrud-
ing safety valves and expansion of the smoothing capacitor.
2. Retighten the bolts of input terminals L1, L2, and L3.
3. Retighten the bolts of output terminals T1 and T2.
4. Re-insert the optical fiber cable connector.
5. Retighten the screws and bolts inside the Power Cell Panel.
Check the main circuit fuse and control circuit fuse.
Check for discoloration and looseness.
6. Clean the heat sink.
If dirt and dust have accumulated on the heat sink, use dry air of 39.2 × 10
4
to 58.8×10
4
Pa (4 to 6 kg·cm
2
) to
clean it.
Fig 8.2 Power Cell Input Voltage Measurement
L11
L12
L13
T1
T2
L21
L22
L23
T1
T2
L31
L32
L33
T1
T2
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