Pump Wiring

[j48j48]

I want to wire a 10 hp 220 V. irrigation pump. It is single phase motor and I have a timer and low pressure kill I would like to hook up also. The motor is rated at 42 amps, do I need a 40 amp breaker or a 50 amp, will I need a pump starter relay in the circuit, and does it need to be 40 amp or 50 amp? I am not an electrcal genuis, but I can follow a diagram. Any help is appreciated. Thanks, J48 /forums/images/graemlins/confused.gif

 

[Philip_L]

This is what I would do:
1. Purchase a 50A contactor (110V coil voltage) with an adjustable thermal overload relay (32-42A)
2. Wire a switch to energize the contactor.
3. With the pump running under full load, measure the current draw of the motor with a clamp on ammeter and set the thermal overload relay just above the amperage.
4. You can wire the timer and low pressure kill switch in series with the contactor coil voltage

If this is confusing, let me know and I can give you more detail. I would by the below components:

contactor:
http://web2.automationdirect.com/adc/Shopping/Catalog/Motor_Controls/Fuji_Contactors_-z-_Overloads/32_to_50_Amp/SC-E2S-110VAC

overload relay:
http://web2.automationdirect.com/adc/Shopping/Catalog/Motor_Controls/Fuji_Contactors_-z-_Overloads/32_to_50_Amp/TK-E2-4200

aux contacts:
http://web2.automationdirect.com/adc/Shopping/Catalog/Motor_Controls/Fuji_Contactors_-z-_Overloads/32_to_50_Amp/SZ-AS1T

Atomation Direct sells good quality components and the price cannot be beat. I use them at work all the time

later and goodluck

 

[Egon]

Just curious. Will startup amperage affect the set up?

</font><font color="blue" class="small">( 3. With the pump running under full load, measure the current draw of the motor with a clamp on ammeter and set the thermal overload relay just above the amperage )</font>

Egon

 

[j48j48]

Thanks for the reply Philip, I was wondering about the start up amperage. Will it cause problems? According to the pump performance chart that came with the pump, I should be at about 75 to 80% percent on the curve. Motor should be about 32 to 34 amps at that load I'd guess. Your components look like what I need also. Thanks j48

 

[Philip_L]

The current draw initially at startup may indeed be higher, but the components will be fine up to 600% of their designed operating conditions. When I was talking about measuring the current with the meter, I meant after the pump had reached base RPM and was runing smoothly, not at startup. Note: the overload relay does not kickoff as soon as the current reaches the limit, there are 3 classes (Class 10-30) This relates to the numbr of seconds before it trips
later