ABB PSTX370 Service Manual page 77

4. Switch the Megger cables
Switch the connection according to figure 6:
1
Connect the red megger contact to the main
terminal 1L1 on the Softstarter.
2
Connect the black megger contact to the main
terminal 2T1 on the Softstarter.
3
Set the megger on 500V. Press and hold the
Test button. Note the result.
Repeat step
5. Connect the Megger to the Softstarter
and
6. Switch the Megger cables
on the two remaining phases between
3L2 - 4T2 and 5L3 - 6T3.
5. Detect a shorted SCR
The three different phases will give six values.
If any of the values shows lower than 1 Mohm there
is probably a shortage. Proceed with changing the
SCR, see chapter 4.7.1 Change the SCR.
6. Connect SCR cables to PCBA
When reconnecting cables; read markings on the
PCBA bracket.
1
Thread all three SCR cables through the cable
inlets on the PCBA bracket.
2
Connect the three SCR cables, according
to previously made markings (1, 2 or 3), to their
terminals on the PCBA.
7. Place front cover
1
Place back the PCBA and the bracket on the
Softstarter.
Place the front cover on the unit and align it to the
plastic screw sleeves located on lower housing.
2
Fasten the front cover with (4x)
x80/10 (1,6Nm).
3
Fasten (1x) Torx 15 M3,5x12 (0,5 Nm)
on the HMI bracket.
REASSEMBLE THE SOFTSTARTER
Connect main power cables and control
cables
Connect the main power cables and the control
cables as described in chapter 4.3.4, step 1-2.
8. Examples of SCR for PSTX
Figure 8 shows typical types of SCR blocks used
in PSTX210...370. The manufacturing type can
be both IXYS (black housing) and Semikron (white
housing).
9. Examples of SCR for PSTX
For Softstarters type PSTX470...570 we are using
SCR of capsule types. See figure 9.
Depending on type and size, these can show
different values when checking them up. Please not
that this type of SCR has to be correctly mounted
when tested to get the correct result.
4
M
OFF
250V
500V
1000V
6
7
Torx 20 4,0
8
9
1SFC13105M0201
1
3
M
M
OFF
250V
500V
1000V
2
2
1
3
Tx 15 (0,5 Nm)
M3,5 x 12
2
1
| Service Manual | Service PSTX470...570
4.8.1_4
4
4.8.1_6
Tx 20 (1,6 Nm)
M4 x 12
4.4.3_11
3.7.1_8
3.7.1_9
77