Overload Curve
Overload Curve
(OP)
When coordinating a typical motor circuit (LV breaker, contactor, and overload relay) with upstream device, should we plot the TCC of LV breaker only? Or should the TCC of overload relay be drawn as well? If we draw the TCC for overload relay, then should it overlap the thermal part of the LV breaker?






RE: Overload Curve
RE: Overload Curve
RE: Overload Curve
Bob
RE: Overload Curve
This is not true. Instantaneous trip only molded case circuit breaker are commonly used in the US for combination motor starters and have been for at least fifty years. The term "motor circuit protecter" or MCP refers to a molded-case circuit breaker with no thermal element. Thermal-magnetic breakers can be used also.
RE: Overload Curve
If you use a factory built starter with a Mag. Only breaker, then you WOULD include the OL relay thermal curve, because THAT then becomes the long-time over current protection for the circuit.
"Will work for (the memory of) salami"