Checking diodes, IGCTs and IPS PCS 6000 system power distribution cabinets FRM70 3BHE034911R0001
Date: Sept 10, 2025Views:
Dangerous voltage inside the PCS6000 can lead to life-threatening situations, injury of the persons involved or damage to equipment.
When planning and carrying out maintenance work, the operating condition of the whole system should be considered.
High temperatures, risk of burns!
Rails, reactors, resistors and fuses can be hot.
Cooling fans can start automatically!
The water cooling system and the cooling fans may start automatically as soon as the auxiliary voltage is switched on or when the EMERGENCY OFF button is released, even if the PCS6000 is de-energized.
Switch off the corresponding motor protection switches (see diagrams contained in the cabinet specific documentation, tab 2) to shut down the cooling system.
Electrostatic discharge (ESD) can damage electronic boards and components!
DO NOT touch printed circuit boards or other sensitive components without applying static-sensitive handling precautions!
While working with components containing printed circuit boards, use a wrist strap which is earthed at the unit's frame.
Whenever components need to be replaced use an antistatic mat on a table near the unit and connect the mat to the same point as the wrist strap.
Hold a board only at the edge.
Handle a faulty board as carefully as a new one.
Fault Identification in triple stack (POM)
The service work described in the following chapter always has to be done after a firing through of the converter. A firing through is usually triggered by a power semiconductor (diode or IGCT) failure. The work includes:
– Test of all IGCTs / identification of faulty IGCTs
– Replacement of faulty IGCTs
– Test of all diodes / identification of faulty diodes
– Replacement of faulty diodes
– Test of replaced IGCTs / diodes
NOTE – For checking the IGCT and diodes the usage of the FADEC 3 is recommended. See section section 9, Checking diodes, IGCTs and IPS, page 115 and the “PCS6000 user manual”, 3BHS600000 E40.
Semiconductor checking sequence
Fig. 9–5 shows the semiconductor orientation and the following checking sequence:
1. Check LEDs of IGCTs.
2. Measure freewheeling diodes.
3. Measure neutral point and clamp diodes.
4. Measure IGCTs
Checking IGCTs with FADEC 3
Faulty IGCTs can be found by the three LEDs mounted on the gate unit. The gate unit has to be switched on and must not receive a trigger signal. This means, before checking the LEDs, the fault must be reset.
IMPORTANT! Before resetting the alarm, “PCS6000 HMI” must be checked for any additional trips or alarms. Any trips or alarms need to be noted down before resetting
The yellow LED indicates the state of the internal voltage controller (20 VDC) and the green
LED gives information about the state of the gate-cathode circuit of the IGCT. The red LED indicates a general malfunction.
1. Check the input and output voltages of the IPS in reference to electrical drawing 3BHE031194E16 (POM) and Table 9–3 using a multimeter.
IMPORTANT! There is a remote possibility of the IGCT being faulty, despite the LEDs showing no error. Therefore, following tests with the FADEC 3 need to be carried out additionally. For more information, see the “FADEC 3 User manual”, 3BHS537463 E72.
3. Switch off MCB -Q401 to interrupt the 3AC 400 V input voltages of the AC/DC converter (24 V power supply).
4. On the UPS -G402 turn the selector switch “Bat.-Select” to “Service”, then back to “7.2
Ah” (Fig. 8–11 in section 8.8, Replacing PECINTM, page 97) to interrupt the 24 V battery supply voltage (the yellow LED “Bat.-Mode” must be dark).
5. Starting the measurement according “FADEC 3 User manual”, 3BHS537463 E72.
Follow the test sequence according to section 9.5, Semiconductor checking sequence, page 121.
If red LED lights up a short circuit inside of the semiconductor is measured. The buzzer tweets twice. The IGCT needs to be replaced according to section 10.6.4, Replacing IGCTs, page 149.
Checking power diodes with FADEC 3
Preparation for checking power diodes
1. Shut down the PCS6000 according to the “PCS6000 Lockout/tagout procedure”, 3BHS600000 E22.
2. All semiconductor stacks are tightened.
3. All broken IGCTs have been replaced.
4. No components in the converter are removed.
5. Switch off MCB -Q401 to interrupt the 3AC 400 V input voltages of the AC/DC converter (24 V power supply).
6. On the UPS -G402 turn the selector switch “Bat.-Select” to “Service”, then back to “7.2 Ah” (Fig. 8–11 in section 8.8, Replacing PECINTM, page 97) to interrupt the 24 V battery supply voltage (the yellow LED “Bat.-Mode” must be dark).
9.7.2. Checking freewheeling diodes
1. Carry out the preparation procedure according to section 9.7.1, Preparation for checking power diodes, page 123.
2. Starting the measurement according to the “FADEC 3 User manual”, 3BHS537463 E72.
3. Follow the test sequence according section 9.5, Semiconductor checking sequence, page 121.
4. If red LED lights up a short circuit inside of the semiconductor is measured.
The buzzer tweets twice. The diode needs to be replaced according to section 10.6.5.1,
Replacing freewheeling diodes, page 153.
IMPORTANT! Pay attention to the correct polarity of the diode and the probes. The plus probe must always be connected to the anode (1) of the diode and not the cathode (2).
Checking clamp diodes
1. Carry out the preparation procedure according to section 9.7.1, Preparation for checking power diodes, page 123.
2. Follow the test sequence according section 9.5, Semiconductor checking sequence, page 121.
3BHS600000_E80_RevF_Service_Manual_PCS6000 Checking diodes, IGCTs and IPS (1).pdf
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