ATS Testing

[anbm]

When they test ATS with both normal and emergency power source on, there is a surge current presented at one of the current phase momently. This phase sync problem/over current condition is causing the trip flag (Pop out Indicator) at the elec. switchboard serving ATS to release and light up a fault indicator LED, indicating an instantaneous trip without tripping the breaker. The ATS has "Phase Rotation Monitor" set to "OFF" position.

Does anyone know what is the "Phase Rotation Monitor" feature in ATS do?

 

[iwire]

The phase rotation monitor is not the cause of this, that makes sure the noramal supply and generator supply are both in the same rotation.

I take it the trip happens when the ATS switches back from the generator to the normal supply?

If this is the case I would see if your ATS can be programed to pause for a second between it opening the generator circuit and closing into the normal circuit.
This allows any motors and transformer to go to zero volts before being re-energized.

It is often called 'transition delay' or 'delayed transition' by the ATS makers.

 

[anbm]

Thank you.

 

[ATSman]

Inphase Monitor Feature

Inphase Monitor Feature

When they test ATS with both normal and emergency power source on, there is a surge current presented at one of the current phase momently. This phase sync problem/over current condition is causing the trip flag (Pop out Indicator) at the elec. switchboard serving ATS to release and light up a fault indicator LED, indicating an instantaneous trip without tripping the breaker. The ATS has "Phase Rotation Monitor" set to "OFF" position.

Does anyone know what is the "Phase Rotation Monitor" feature in ATS do?

iWire's suggestion only applies to an ATS that is a 3 position design (neutral)
and the middle position time can be adjusted (typically 5 sec) in the menu of the microprocessor or on a separate timer relay. If it is a 2 position ATS then check if the Inphase Monitor is enabled. This assures synchronism between sources before transfer and limits the load current inrush which sounds like what is causing the target to trip. Also chek the instantaneous setting on the circuit breaker at the switchboard and make sure it is not set to low. If so raise the setting to high or 10X to account for this inrush.
Tony