Leybold 3~ Time Over/undervoltage relay coordination

[KHA_LED]

Hi all
please could you provide more informations about the coordination of this relaly with the power circuit breaker

 

[thermionic1]

Not much information here.

Leybold appears to make vacuum pumps. I'd imagine the undervoltage is to protect the motor once running, with a small time delay. I'd image the overvoltage would block closing the breaker to protect the motor.

Who knows really without more information.

 

[waross]

I would consider the effect of over-voltage on the loads and set the trips accordingly.
In an area where the utility was known for mistakes, I put an instantaneous overvoltage trip on a set of relays and wired the control circuit of each refrigerant compressor through the relay set.
This was a sausage factory with a lot of refrigeration, for both raw supplies and finished product.
Sure enough, came the day when the utility changed out a transformer bank and fed 416 Volts into a 208 Volt service.
Not one refrigeration system was damaged and no product was lost.
Your voltage relay is not to protect the breaker, it is to protect the load.
You haven't told us anything about the loads.

 

[KHA_LED]

I would consider the effect of over-voltage on the loads and set the trips accordingly.
In an area where the utility was known for mistakes, I put an instantaneous overvoltage trip on a set of relays and wired the control circuit of each refrigerant compressor through the relay set.
This was a sausage factory with a lot of refrigeration, for both raw supplies and finished product.
Sure enough, came the day when the utility changed out a transformer bank and fed 416 Volts into a 208 Volt service.
Not one refrigeration system was damaged and no product was lost.
Your voltage relay is not to protect the breaker, it is to protect the load.
You haven't told us anything about the loads.

Sure, I'll add some information for examples, the protected load is a variable resistive load.
I'll add the other experimental blocks to clarify more.
This is practically the main association of the rest of the experimental blocks.

​

 

[waross]

You want to protect the transformer from over-voltage and saturation.

 

[KHA_LED]

You want to protect the transformer from over-voltage and saturation.

I want to protect the load from over-voltage and under-voltage when the resistive load changes. I mean, after gradually changing the load, we observe the load voltage and check the relay's behavior in response to these changes.

 

[waross]

Over-voltage:
In most cases the transformer will be damaged before a resistor bank.
If this is a special application, then set the relay to open the breaker at the maximum allowable voltage.
Under-voltage:
In most cases this is not a concern with a resistor bank.
If this is a special application, then set the relay to open the breaker at the minimum allowable voltage.
Will the relay be on the transformer primary or on the transformer secondary?
Depending on your circuit, you may have to bypass the relay in order to close the breaker.

 

[KHA_LED]

Over-voltage:
In most cases the transformer will be damaged before a resistor bank.
If this is a special application, then set the relay to open the breaker at the maximum allowable voltage.
Under-voltage:
In most cases this is not a concern with a resistor bank.
If this is a special application, then set the relay to open the breaker at the minimum allowable voltage.
Will the relay be on the transformer primary or on the transformer secondary?
Depending on your circuit, you may have to bypass the relay in order to close the breaker.

on the transformer secondary

 

[waross]

on the transformer secondary

If you are using this to trip the breaker:

you may have to bypass the relay in order to close the breaker.

 

[KHA_LED]

If you are using this to trip the breaker:

But the relay here send an information to the breaker to open the circuit,
What do do you mean by ''bypass it'' ??

 

[waross]

What do do you mean by ''bypass it'' ??

Breaker open = no voltage at the relay.
Depending on the relay the relay may prohibit the closing of the breaker.

 

[KHA_LED]

Breaker open = no voltage at the relay.
Depending on the relay the relay may prohibit the closing of the breaker.

Got it, thanks a lot