Relationship between the specified rated current of the pumps in the power distribution room and the rated current of the pumps on-site
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As a layperson, I have a small question: what is the relationship between the specified rated current of the pumps in the power distribution room and the rated current of those pumps in actual use? Is the rated current of the motor pump specified by the power distribution room 90%~110% of the rated current of the motor pump on site? I would appreciate your advice! The question might not be very clear; please point it out!
Generally, the current set for the earliest thermal relays is 1.05 to 1.1 times the rated current.
I just don’t quite understand the specific rules. Because the rated current of one pump in our unit is 133A, while that in the distribution cabinet in the central power room is 90A; we hope everyone can help clarify this issue!
The setting of the thermal relay should be determined based on the actual current of the motor, rather than its rated current. First, measure the actual operating current of the motor, and then set the thermal relay to 1.1 times that current.
But what if the motor is faced with different loads, such as an oil pump? The reaction tank has specific temperature control requirements; when the temperature approaches the set point, the control valve will close. Will the pressure in the pipeline increase at that time? Will the current of that pump be higher than that at 100% normal operation?