maximum distance from pump control panel to level switch

Charbel · Nov 17, 2014

Dear,

I am using in a pump control panel a relay connected to a high level switch that will stop the pump in case of high level in the receiving tank.

from the attached datasheet i can depict that the current needed for the level switch would be 0.08A at 240 VAC.
And considering an allowable 3% drop in voltage and for 1.5mm2 cable size, i got a value of 5118 meter which is 2559meter of cables run.

i really appreciate if you have any concern concerning the above. Any special requirements for the relay?

thank you!

Charbel

Eric Nelson · Nov 17, 2014

Charbel said:
the current needed for the level switch would be 0.08A at 240 VAC.

The switch itself does not draw any current. The 0.08A and 240VAC are simply the max. ratings for the switch.

-Eric

Charbel · Nov 17, 2014

Dear Eric,

yes, true, i was considering in the calculation the maximum current that can be withdrawn.

thank you!

Charbel

Lancie1 · Nov 17, 2014

yes, true, i was considering in the calculation the maximum current that can be withdrawn.

0.08 Amps does not seem to be enough to energize a pump motor starter. Check the pull-in or inrush current for whatever device (contactor coil, relay, PLC Input) is connected to the 0.08-maximum level switch.

Charbel · Nov 18, 2014

Dear lancie,

thank you for your reply, please see attached, the inrush power is 200 VA which is around 0.909 A at 220VAC, shall i take this value in my calculation considering that the maximum current that the level can whitstant is 0.08A.

thank you for your valuable advice,

Eric Nelson · Nov 18, 2014

Lancie is correct. You don't want that switch directly controlling your contactor. Even the holding current is at the limit of the switch's capacity. Have the switch energize a small interposing relay, and let that relay control your contactor.

-Eric

Charbel · Nov 18, 2014

please find attached the selected interposing relay, what is the current withdrawn to be selected in the calculation of the cable length indicate above?

thanks a lot!

nonuke · Nov 18, 2014

This relay will be OK. You just have to make sure the coil voltage will not drop bellow 176VAC according to specs.

osmanmom · Nov 18, 2014

how much the cable cost for 2559 meter

maximum distance from pump control panel to level switch

Charbel

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