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Old 04-11-2010, 12:51 PM   #16
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Float switch with contactor and pump


This is a 220/380 3 phase wye connected system. There is 380 volts phase to phase, and 220 volts phase to neutral. If the neutral is present, a 220 volt coil will work.

A contactor will control the motor, but it will not protect the motor. For that, you'll need an overload block. The Telemecanique LRD series will work, and it'll mount right to the contactor. You'll need the full-load current of the motor as well as the service factor (S.F.) current to get the right one. For a submersible pump motor, use class 10.

A single float can be used to control the contactor, but the 'dead zone' might not be enough. The 'dead zone' is the distance the float moves between turning on and off. It's usually less than an inch.

To fill the tank more than that, you'll need two floats. One will start the pump, the other will stop it. For this set-up, you'll need to use the NO contact.

It's pretty simple to hook up either type, but we'll need to know whether you're using one or two floats, and whether or not there's an overload block.

Rob

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Old 04-11-2010, 01:09 PM   #17
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Float switch with contactor and pump


If you want the tank to go from full to half and back, then you will proably need two float switches and use the N/O side switch.

If you use only one switch then you will not need the side switch.
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Old 04-11-2010, 02:51 PM   #18
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Float switch with contactor and pump


Thanks for replys,

I think my above explanation is not correct,

just a simple question,

I have the following things,

1. Contactor(lc1d32) - 3 phase 400 volts( with NO,NC and coil A1,A2 220 volts)
2. Float switch with 3 wires(Brown,Black, Blue) 220 volts, in which brown is common
3. Selector switch (auto/off/hand)
4. Submersible pump - 3 phase 400 volts
5. Power source 3 phase(L1,L2,L3) 400 volts with netural

I have 5000 gallon of tank and water is filling in it from the well(with submersible pump) and every time i have to fill manually when its get empty, to avoid this i want to make it automatic filling. i have the following above things to do it automatic but iam not sure how to wire(connect) all together , can any one explain me how to connect the above things together?.

Thanks
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Old 04-11-2010, 03:34 PM   #19
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Float switch with contactor and pump


Assuming the power in and out are done, connect the incoming neutral to A1.

Pick any one of the incoming hots, and connect it to one side of each block on the H-O-A switch.

Connect the other side of the 'hand' block to A2.

Connect the other side of the 'auto' block to the common of the float switch. I don't know which color it is, if you don't have a diagram of it, post back, we'll help you determine what colors go where.

Connect the NC side (also known as 'close on fall' or 'open on rise') of the float switch to A2. (Two wires on A2).

This control scheme will result in the pump running when the switch is in hand. It'll ignore the float. When the switch is in auto, the pump will run only when the float tells it to. When the switch is off, the pump won't run at all.

Note: Unless there's properly sized fuses or an overload device somewhere between the power source and the motor, there isn't any protection for the motor. If voltage drops too low, or phase imbalance is too great, the motor will burn up. Depending on the size of the fuses or circuit breaker ahead of the contactor, the control circuit might not be protected.

It's also possible, depending on what type of float you have, that the float will start the pump, it'll run for a short time, then the float will stop the pump. If this is not good, you'll need two floats, and the control wiring will be a bit different. Also, if waves in the water cause the pump to start and stop rapidly, it'll burn up either the motor or the contactor. Two floats will solve this as well.

Rob

Last edited by micromind; 04-12-2010 at 12:29 AM.
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Old 04-11-2010, 05:29 PM   #20
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Float switch with contactor and pump


Protection for the pump motor is a brand new topic.
Protection for the motor is normally not achieved using the contactor or the coil circuit.
The motor may include a built in thermal circuit breaker to protect against overheating.

If a second float switch is used to turn off the pump, that switch will exert total control over the pump by turning the pump back on when the water level drops just a little.
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Old 04-11-2010, 05:40 PM   #21
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Float switch with contactor and pump


you might want to check the action of the contacts in the float. There are such things as a wide angle action that would work well for you. It closes the contacts when down and opes when up but it is designed to extend the "dead zone" as micromind called it.


If such is not available to you, you sill most likely want to use 2 float switches and a relay to control on and off actions of the control circuit so to allow the pump to pump until the tank is full enough for you.


If you use just one float switch with a typical "dead zone", depending on how much water you use and the size of the tank, you may end up cycling the pump too often and cause undue wear from frequent starts.
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Old 04-11-2010, 09:08 PM   #22
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Float switch with contactor and pump


Quote:
Originally Posted by micromind View Post
The NO and NC are used only with momentary devices, like start/stop buttons. If the float is a maintained contact, just wire it in series with the coil.

NO and NC are not used with maintained contacts.

If there are two floats (one to start the pump, the other to stop it), then the NO and NC are needed.

Rob
Some models of float switches DO come with NO and NC contacts. But they're optional. It could be wired for NO or NC. But not both. The float switch has Three terminals. One is COMMON. (Hot) The others are (1) NO; (3) NC.!
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Old 04-11-2010, 10:07 PM   #23
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Float switch with contactor and pump


The NO an NC contacts I was referring to are located on the motor starter contactor, not the float.

Please read each post very carefully, including context before you criticize a reply.

Rob
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Old 04-12-2010, 07:19 AM   #24
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Float switch with contactor and pump


The schematic for the contactor as shown here has three normally open contacts for the 3-phase power to the motor, a fourth contact that is normally open (marked NO) and a fifth contact that is normally closed (NC). (portion deleted)

The float switches mentioned have three wires each so they also probably have contacts you can call NO and NC. I don't know which one should be labeled which. You need the 3 wire float switches for a generic pump that might be used to either fill up a tank or basin or empty out a sump (water collecting pit).

(portion deleted)
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Last edited by AllanJ; 04-12-2010 at 09:52 PM.
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Old 04-12-2010, 08:10 AM   #25
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Float switch with contactor and pump


The NO contact on the starter is usually used with start-stop pushbuttons. It serves as a latch to hold the starter closed once the start button has been pushed. It remains energized through the stop button.

If two floats are used, the bottom one is used as the start button, and the top one is used as the stop button.

This way, once the liquid level has triggered the bottom float, it energizes the coil, and is held in by the NO contact.

When the liquid level reaches the top float, it de-energizes the circuit, and the NO contact opens, thus releasing the latch.

The contact of the bottom float has to be open, and close on falling liquid level. The contact of the top float has to be closed, and open on rising liquid level.

Rob
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Old 04-12-2010, 01:11 PM   #26
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Float switch with contactor and pump


Quote:
Originally Posted by micromind View Post
The NO an NC contacts I was referring to are located on the motor starter contactor, not the float.

Please read each post very carefully, including context before you criticize a reply.

Rob
I've read your reference to the Motor Contactor (a/o) to the float switch, and my comment wasn't meant to criticize, just to throw that in. If the implication was that I criticized, my strongest apologies to you!!!!
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Old 04-12-2010, 07:13 PM   #27
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Float switch with contactor and pump


I have to apologize too, it was kind of a lousy day, I didn't mean to take it out on anyone.

Rob

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