Photo Sensor Voltage

I have an omron E3F2-R2Z1 photo sensor connected to a 125v source and attempting to drive a delay relay. When the sensor switches it outputs 125vac however, when the switch is open it outputs 45vac. Any ideas where I'm going wrong? Also, in P.E. switch characteristics, the control output spec. usually mentions residual voltage. Could someone briefly explain this parameter?

Thank You
Joe

Your photoeye is a solid state device with a transistor output. If it doesn't see any load there will be some leakage voltage present (or leakage current depending on who you are arguing with). Your relay is also solid state so it does not provide enough of a draw to "pull down" the transistor in the photoeye.

The easy fix to this is to put a resistor tied to your photoeyes output wire and neutral (about 1k). That should fix you up.

This same phenomenom "gets" a lot of new PLC users using triac output cards. If you don't have a load on the output and the output is off, you will still measure 120V with a meter (because a meter is a high impedance device). If you use something like a wiggy or a light bulb it will load the output and show that it is off.
Now that I mentioned "leakage voltage" and "wiggy" in the same post things should take off.

I am making an assumption in all of this that your time delay relay is actually solid state.

allscott said:

Now that I mentioned "leakage voltage" and "wiggy" in the same post things should take off.

Click to expand...

How dare you!

mdeltat said:

...mentions residual voltage...

Click to expand...

It might also be called leakage current and be specified in micro- or milli- amps.

allscott said:

Your relay is also solid state...

Click to expand...

Do you have ESPN? Couldn't an electromechanial relay do that too?

allscott said:

Now that I mentioned "leakage voltage" and "wiggy" in the same post things should take off.

Click to expand...

Yup, especially after miller time on a Friday night...

:nodi:

OkiePC said:

Do you have ESPN? Couldn't an electromechanial relay do that too?



:nodi:

Click to expand...

I do have ESPN, I like golf. I don't have ESP though

See my note on the bottom, yes this could be a mechanical type relay but since I think this is a new installation I assumed it was solid stete.

allscott said:

The easy fix to this is to put a resistor tied to your photoeyes output wire and neutral (about 1k). That should fix you up.

Click to expand...

On 125 volts with a 1k resistor W=V2/R
125x125/1000= 15.625 watts of heat when PE is turned on.

You are on the right track but I would go with a 5k resistor
that gives off 3.125 watts of heat when PE is on.

You are right, however I think (pretty sure) that a 1K load would be enough to load the transistor enough that it wouldn't leak.

This unit appears to leak a fairly large amount even under load.

allscott said:

You are right, however I think (pretty sure) that a 1K load would be enough to load the transistor enough that it wouldn't leak.

Click to expand...

We haven't been given the details of the timer relay, but if it is one of those 12 to 240 volt units, then this might just be a rather bad combination of hardware.

First -- A sincere thanks for an unexpected volume of knowledge sharing.
Second -- Let's say hypothetically that "my friend" was using one of those 12 to 240 volt units...what would prove a more educated selection for future projects?
Third -- I have two relays. An ON Delay and an OFF delay, why does the off delay include an external switch connection but not the ON delay? This relay is the DAyton 1EGC3 but I havew seen this with other manufacturers as well.

Thanks Again!!

I can help with the 3rd question:

An on delay timing relay doesn't require any power except when the ciruit it is timing is powered.

An off delay timing relay still needs power after the circuit it is monitoring goes off.

Most time delay relays offer both modes, and you add a jumper wire to select between the two (or more) modes.

So the input contacts need to be continuously powered while the external switch contacts are connected to the switch that is being monitored?

mdeltat said:

So the input contacts need to be continuously powered while the external switch contacts are connected to the switch that is being monitored?

Click to expand...

Correct. It might help to think of the input contacts as power supply contacts, as that is actually what they are in this instance.

milldrone said:

This unit appears to leak a fairly large amount even under load.

We haven't been given the details of the timer relay, but if it is one of those 12 to 240 volt units, then this might just be a rather bad combination of hardware.

Click to expand...

That looks like a spec for voltage drop when operating the unit at full rated load. The sheet didn't seem to specify what the leakage current would be.

Here is a spec sheet (for a different sensor) that breaks it down a little more clearly.


To the OP, what is your relay doing? You haven't described the problems you are having (if any) other than noting a 45V signal when the PE is off.

Brian

Brian123,

Brian123 said:

To the OP, what is your relay doing? You haven't described the problems you are having (if any) other than noting a 45V signal when the PE is off.

Brian

Click to expand...

Are you speaking to the OP or his "friend"?

mdeltat said:

Let's say hypothetically that "my friend" was using one of those 12 to 240 volt units...what would prove a more educated selection for future projects?


Thanks Again!!

Click to expand...

mdeltat said:

I have an omron E3F2-R2Z1 photo sensor connected to a 125v source and attempting to drive a delay relay. When the sensor switches it outputs 125vac however, when the switch is open it outputs 45vac. Any ideas where I'm going wrong? Also, in P.E. switch characteristics, the control output spec. usually mentions residual voltage. Could someone briefly explain this parameter?

Thank You
Joe

Click to expand...

He incriminated himself in the first post. No take-backs.

Brian