Causes And Troubleshooting Shorted SCRs On Softstarters | Sprecher + Schuh (2024)

Questions:

What does it mean when a soft starterLED flashes six (6) times for PCS/PCE or PF LCD displays F4/F5/F6 to indicate ashorted SCR error? How can I verify and what tests can be performed to determine if an SCR is shorted? How can I trouble shoot and clear this fault? Can I over ride this fault?

Some Causes Of Shorted SCRs In Softstarters:

• Loose 3 phase power connections or damaged conductors on line side of the PCS/PF/PCE controller
• Wire conductor damage on the load side of the PCS/PF/PCE controller to the motor
• Damage to windings inside the motor
• The PCS/PF/PCE control module has sustained physical damage to control circuit board components
• Power surges, spikes, disturbances, over voltage conditions present in the 3 Phase Power distribution circuits can cause SCR's to breakdown and short
• Excessive levels of voltage and current present in the three phase power supply to the PCS/PF/PCE soft starter can cause SCR's to breakdown and short

Troubleshooting:

The shorted SCR check is performed internally by the PCS, PF or PCE softstarter as a pre-start check. A start command will not be issued to the softstarter if a Shorted SCR condition is detected.
Note: Shorted SCR Faults cannot be overridden through a parameter change for PF or dip switch change for PCS/PCE.

See The Following Steps Below To Troubleshoot And Resolve These Faults:

1. Verify the PCE dip switch 15, or PF motor connection selection is set to the proper motor connection type. Set it to Line Connection for three lead Motors (Dip switch 15 Up for PCE); set it to Delta Connection for six lead Wye Start Delta Motors (Dip switch 15 Down for PCE).
2. Verify 3 phase power connections on line side of the PCS/PF/PCE controller are tight; correct damage to conductor cables.
3. Verify conductors on load side of the PCS/PF/PCE controller going to the motor are tight; correct damage to conductor cables.
4. Verify motor windings are not damaged by meggering the motor.Remove motor leads from the PCS/PF/PCE controller before using a Megger to measure and test the motor windings.
5. If the PCS/PF/PCE soft starterhas the shorted SCR error, performresistance checks across each ofthe power poles (L1 to T1, L2 to T2, L3 to T3).
6. The resistance check across all 3-phases should be 10,000 ohms or greater if the SCR is okay and isnotshorted. A shorted SCR will have much less resistance than the normal 10,000 ohm reading.Before performing these checks, do the following:
   • Remove the motor leads from the bottom of the PCS/PF/PCE soft starter
   • Remove three phase and control power from the PCS/PF/PCE soft starter

For additional information please contact yournearest authorized distributor,sales representative, or call our customer service ortechnical supportlines.