Help with wiring Single Point Level Switch

jbonest

Member
Location
chicago,IL,USA
I have tried to wire this Single Point Level Switch and I have had no luck . attached is the schematic


The output is a SPDT relay (10A @ 115 V). I am testing this with a DMM

Green is to 1, Black is to 2, white is to 3 . Are 2 and 6 internally connected??? If I measure with meter 3 and 6 shouldn't I get the same voltage as the input. If I I measure 2 and 4 I get a reading of 14V . Nothing happens when the probe hits the water. I know this is pretty vauge just looking for a little help .

Thanks

J
 

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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
There is a jumper shown between 2 and 6. You need to add it.
The jumper is, IMHO, drawn the way it is because it is optional depending on how you want the relay to operate. If you want dry contacts, leave the jumper off and wire whatever you want to the COM terminal, 6.
If you want to have switched line voltage on the relay outputs (as required for the alarm/control circuit shown in this schematic), add the jumper.
I agree that in the OP's case he probably want to add the jumper.

The measured 14V is almost certainly phantom voltage.
 

jbonest

Member
Location
chicago,IL,USA
The jumper is, IMHO, drawn the way it is because it is optional depending on how you want the relay to operate. If you want dry contacts, leave the jumper off and wire whatever you want to the COM terminal, 6.
If you want to have switched line voltage on the relay outputs (as required for the alarm/control circuit shown in this schematic), add the jumper.
I agree that in the OP's case he probably want to add the jumper.

The measured 14V is almost certainly phantom voltage.



Can I test this by wiring a light bulb to the NC or NO outputs. Connect one to there and the other to another source??
 

gar

Senior Member
160624-1523 EDT

jbonest:

First, you need to understand how various electrical components work. An understanding of what may be inside of this "black box" is next. This is going to be a guess without opening the device. Any specific written information on how the device works is quite important.

From the information you have provided this appears to be a liquid level control, and of a single point type. That would imply an on-off operation at a single point. What is supposed to be the theory of operation relative to detecting water or some other liquid. Is this a conductive, capacitive, inductive, optical, thermal or other type of liquid level sensor? My guess is it is a conductive sensor. Can it detect distilled water, or oil?

You need to know its theory of operation. Does it use a DC or AC voltage for sensing? Is this sensing voltage isolated from the AC power source? What is the sensing voltage magnitude? Over what resistance range is the sensing threshold adjustable?

From the information you have provided we can guess that there is internally at least a transformer, and an electromechanical SPDT relay. This relay has two states. We assume the the relay marking means that the NC contact is closed when there is no liquid contact, and thus a pump motor should run under these conditions. If this contact is also closed when no input AC power is applied, then this is not a fail safe design. However, deriving input power to the relay contact from the same source as the input to the control does make it fail safe.

I would use the ohmmeter function of your meter to check for continuity from each of the AC input terminals (L and N) to the relay COM terminal. Obviously done with no input AC power. From your measurements I assume a relatively high resistance. Probably above 1 megohm.

With no input AC power applied is COM to NC open or closed? With your probe in free state does COM to NC change state whren AC input power is applied? If it changes state, then at least part of your control works.

You need to know what the maximum probe voltage is and if you touch the probe can you get hurt. What two terminals define the probe circuit? One is the probe, I have to assume the other is the ground terminal. With power input present short the probe to the ground terminal. You should hear a mechanical click inside the "black box". I am assuming an electromechanical relay as the output for cost and because it is SPDT. As well as hearing a click you should see continuity change across the terminals COM to NC.

Doing these tests on a bench is the best way to study the device.

Provide more information.

.
 

Saturn_Europa

Senior Member
Location
Raleigh, NC USA
Jbonest: "Are 2 and 6 internally connected???"

No they are not. 6 is common to both the N.O. and N.C. Using an ohmmeter you can watch the relay open and close when the probe is wet or dry (make sure jumper from 2 to 6 is not in when you ohm it out) Its a pretty simple set up but can be very confusing the first couple times you wire one up. Play with it for a bit and you'll figure it out. Welcome to the forum!!
 
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