Can someone explain this wiring diagram?

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Old 10-01-19, 10:17 AM
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Can someone explain this wiring diagram?

Focusing on the emptying side.

Which wire is NO, which is NC, are the blues supposed to be tied together or is that just them being labeled? Ive been staring at this for 10 minutes and I can't wrap my head around how the electricity is supposed to flow

 
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Old 10-01-19, 10:39 AM
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I need a second try on this one. Each float switch is a SPDT type. The black wire is the wiper, the blue wire is the NC, the brown is the NO contact.

As the liquid rises on the right side tank, the brown connects to the Black wire on the left switch. The coil is energized and the right switch keeps current flowing until it falls due to low liquid level and de-energizes the relay.

Note that the float contacts are NOT shown. Only the relay NO aux. contact, the three phase contacts, and the overload heaters that control the NC contact are shown.

Yes, the blue wires are connected together on the right tank floats, and the brown wires are connected on the left tank floats.
 

Last edited by telecom guy; 10-01-19 at 11:02 AM.
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Old 10-01-19, 11:02 AM
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I still don't really understand. Are the floats connected to two terminals on the contractor?

I think I'm struggling with it appearing that the control circuit is connected in two places to neutral. Shouldn't there only be one condition (top open, bottom closed) in which the coil is energized?

edit: because I didn't see your edit that helped.
 
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Old 10-01-19, 11:20 AM
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Note that the TOP float switch initially turns on the motor, then is out of the picture. The motor keeps running until the bottom float trips, then breaking the N circuit made by the relay.
If you had a power drop during the pump out, the system would stay off again until the liquid again rose above the top float.
 
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Old 10-01-19, 11:21 AM
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When you say overload heaters you mean the relay that goes between the contractor and the motor? I didn't even realize that was being shown, which wire is being connected to the terminal on the overload heater?

So this is basically set up like a push to start, push to stop motor?
 
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Old 10-01-19, 11:32 AM
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Yeah, that is a typical three phase with overload heater contactor with an aux contact. Many of these have a dial to set the correct run current. Overloads (or a dropped phase) will cause the built-in heaters to drop the coil.


I see now the blue wires on the right side actually do not need to be connected together, or anywhere else. Can be left floating. No doubt the same for the left side brown wires too.

Yes, to your comment. Much like a magnetic starter. A momentary action for both start and stop. And, no auto-restart with a power up.
 
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Old 10-01-19, 10:44 PM
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One last question, Iím going to be using these with 24v not 220 as suggested in the diagram. Iíve noticed in other set ups that the low voltage control circuits are fused. What kind of fuse would I need here and where exactly would it go?
 
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Old 10-02-19, 07:13 AM
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Depends; what is motor rating? What is making the 24V?
 
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Old 10-02-19, 07:33 AM
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Motor is single phase 220v 1.5hp so ~5a. Power from a 12/24 (currently everything on the 24) step down transformer that is used for contractors for 2 other pumps, related float switches, indicator lights and man/auto switches. New pump will have its own circuit breaker and of course it that heater relay on the contactor.
 
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Old 10-02-19, 09:54 AM
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OK, you are saying the controls are going to 24Vac and the power is still 240V.
So, a couple things to note. You can use a 3 ph starter for single phase, but note the wiring of the contactor will still use all three poles in order to work the heaters correctly. THat should be in the wiring instructions of the contactor.

On the 24V ac overcurrent protection; maybe put in a small fuse the same Amp rating as the control transformer, OR insure the transformer is self limiting/short circuit protected.
 
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Old 10-02-19, 10:30 AM
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Iím going to add it to this panel, (I know it looks like a bit of a squeeze but I think if flip the transformer sideways itíll work)

the transformer is currently fused with 4A fuses on both the 220 side and the 24 side with separate individual fuses for the control circuits of the existing pumps. I am I right in assuming I should add another one for this new pump?

 
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Old 10-02-19, 12:41 PM
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Looks like a nice, euro, touch proof design. Hopefully the swing door is also touch-proof, even more essential.

So, same xfmr for all control? You really just need one fuse, unless you want to isolate the bad circuit without affecting the OK ones.
 
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Old 10-03-19, 08:45 AM
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This looks like a supply of 3 phase (R-S-T) and Neutral.
Typical 240V or 400V with 120 or 230V for the contactors. For each 3-phase motor one flater starts the contactor, and the other disconnects it. One system for filling, one for emptying. It is not often but it could even be for a 480/277V system, but 277V contactors are not that commonly used.

I am sitting in Norway, and ar not updated on NEC , but when we built systems for US 480V we used a transformer, and 24V contactors.

The picture looks like an European system.

dsk
 
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Old 10-03-19, 08:53 AM
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by the way look at this: https://www.youtube.com/watch?v=wxe-2wXC4mE
 
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