SDMO ATS Control / Signaling Fault

Automatic transfer switch (ATS) does not transfer to generator during mains failure, although SDMO generator runs normally.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Broken control cable between SDMO controller and ATS, Faulty ATS control relay, Incorrect ATS configuration for SDMO signals, Stuck mechanical interlock in ATS

How to Fix / Troubleshooting

Safety first: Isolate both mains and generator sources before opening the ATS. Only qualified electricians should work on transfer equipment.

  • Verify generator ready signal: Check that the SDMO controller is sending the correct dry contact or voltage signal to the ATS when the generator is ready.
  • Inspect control wiring: Trace the control cable from the generator panel to the ATS. Repair any damaged conductors or loose terminals.
  • Test ATS coils and relays: Manually energize ATS control coils (if safe and per manufacturer instructions) to confirm mechanical operation.
  • Review ATS settings: Ensure that the ATS is configured to accept SDMO generator signals and that time delays are appropriate.
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Repair Difficulty

Hard 4/5

Required Part

Automatic Transfer Switch Control Relay
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