Test The Scr - ABB PSTX370 Service Manual

3.7.1

Test the SCR

IMPORTANT NOTE
Only perform the SCR-test if the
Softstarter displays one of the following
faults: "Short circuit thyristor fault" or
"Open circuit thyristor fault"
Replace SCR if the result of the test
shows under 1 Mohm.
DISMANTLE THE SOFTSTARTER
Remove main power cables and control
cables
Disconnect the main power cables and the control
cables as described in chapter 3.3.1, step 1-3.
1. Remove the front cover
1
Loosen (1x) Torx 15 M3,5x12 on the HMI
bracket.
1
Loosen (4x) Torx 20 4,0 x80/10. Remove
the front cover by lifting it upwards from unit.
2. Disconnect SCR cables from PCBA
Mark the SCR cables with 1, 2, 3 prior to
disconnecting them. This enables proper re-
connection.
1
Disconnect the three SCR cables from their
terminals on the PCBA using a long-nose plier.
2
Slide out the cables from the cable holders
located on bracket.
3. Connect the Megger to the Softstarter
1
Connect the black megger contact to the main
terminal 1L1 on the Softstarter.
2
Connect the red 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.
Also use 500V for 690V softstarters.
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.
1
2
1
3
M
OFF
250V
500V
1000V 1
4
M
OFF
250V
500V
1000V 1
| Service Manual | Service PSTX210...370
1SFC13105M0201
1
Tx 15 Tx 20
M3,5 x 12 4,0 x80/10
2
3.7.1_1
2
3.7.1_2
M
M
250V OFF
500V
1000V
3.7.1_3
M
M
OFF
250V
500V
1000V
3.7.1_4
3
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