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Technical Tips & FAQs
CEP7 Interchangeability of Single-Phase and Three-Phase Overload Relays
Question:
Can you interchange or swap out a single-phase CEP7S-EE__ overload relay with a three-phase CEP7-ED1__/CEP7-EE__ solid-state overload relay? If I wire or loop the single phase power source through the legs of the CEP7 Three-phase solid state relay, will this configuration protect the motor?
Answer:
It is not possible to interchange or swap single-phase and 3-phase overload relays in the CEP7 product line. The reason for this is:
- Each overload (single-phase or 3-phase) is designed specifically for a Single phase or 3 phase motor, not both.
- There are internal firmware/hardware differences between a 3-phase (CEP7) and a single-phase (CEP7S) overload relay.
If a CEP7-ED1__, CEP7-EE__ and CEP7S overloads are interchanged with three phase or single phase loads the following will occur:
- If you use a single-phase overload on the 3-phase installation you may get nuisance tripping.
- If you use a 3-phase overload in a single-phase application you will lose protection. This is because the 3-phase overloads needs to see the 3-phase angles and the microprocessor inside the CEP7 overload requires a 3-phase power source to function correctly.
March 2016
Categories: Motor Protection
1775 ROK26180
