Under-Voltage Trip.

[stgeorge]

I have an 120V "under-voltge" breaker that has tripped. it tripped a while ago and i simply turned it off and turned back on. It has done the same and now does not turn back on. Even when "off" it is still in the tripped position.
There is no reading form the two #14AWG which are 24VDC.
I need to trrouble shoot and correct this issue and am asking for opinions on what and why and how to solve...
Thank you for your help.

 

[jim dungar]

I have an 120V "under-voltge" breaker that has tripped. it tripped a while ago and i simply turned it off and turned back on. It has done the same and now does not turn back on. Even when "off" it is still in the tripped position.
There is no reading form the two #14AWG which are 24VDC.
I need to trrouble shoot and correct this issue and am asking for opinions on what and why and how to solve...
Thank you for your help.

Your undervoltage coil must have 24VDC applied to it, in order to hold the breaker on.

 

[Jraef]

Your undervoltage coil must have 24VDC applied to it, in order to hold the breaker on.

And to further that thought, if the UV coil has had 120VAC applied to it all this time, it's now toast and will not engage even if you do apply 24VDC. :wink:

 

[templdl]

If this is a breaker that has a UVR option, then voltage must be applied to the UVR before one attemps to reset and close the breaker.
Should there be no voltage applied to the UVR when breaker is reset and closed it will immediatly trip befor completely closing.
If one continus to do this the breaker's trip mechanizm can be damaged to the point where it can not be reset.

 

[Cold Fusion]

I have an 120V "under-voltge" breaker that has tripped. it tripped a while ago and i simply turned it off and turned back on. It has done the same and now does not turn back on. Even when "off" it is still in the tripped position.
There is no reading form the two #14AWG which are 24VDC.
I need to trrouble shoot and correct this issue and am asking for opinions on what and why and how to solve...
Thank you for your help.

st -
Perhaps you could give us a bit more information on the cb - like a model number maybe. I'm not at all clear on what a '120V "under-voltage" breaker' is. The picture I have in my mind is a QO with a UV coil??? I didn't know they even existed.

Jim, jaref -
I don't think I have ever seen a CB with a UV coil rated at 24DC. Have either of you?

ST -
Is this cb maybe a shunt trip?

cf

 

[Cold Fusion]

---There is no reading form the two #14AWG which are 24VDC. ---.

st -
I can't tell what the 24vdc is for, so I can't tell if not having it is good or bad.

Is this 24vdc to control the cb or is it maybe alarm contacts in the cb? And how can you tell it is suposed to be 24vdc?

---I need to trrouble shoot and correct this issue and am asking for opinions on what and why and how to solve... .

First thing I'd do is find a schematic or interconnect diagram. It is really hard to troubleshoot without having that.

cf

 

[erickench]

If it's a 24 Volt circuit then of course the 120 Volt undervoltage OCPD is going to trip. The circuit breaker trips whenever the voltage goes below 120 Volts. That's what it's designed for. Seems like you're using DC circuits with an AC device. That's not gonna wash either.

 

[jim dungar]

I don't think I have ever seen a CB with a UV coil rated at 24DC. Have either of you?

Square D:
field installed #S29410 for their new H and J frame breakers
factory installed suffix # -1143 for their traditional line of breakers

 

[erickench]

Question: Is the 24VDC circuit just there for control purposes? If so then I would check the utility voltage and see if it's below 120VAC. Then again you're not getting any reading so maybe the control circuitry isn't energized.

 

[Jraef]

Jim, jraef -
I don't think I have ever seen a CB with a UV coil rated at 24DC. Have either of you?
cf

Done all the time in the semiconductor tooling industry. They use 24VDC in what they call the "EMO" circuit (EMergency Off) where if someone slaps a mushroom head EMO button anywhere on the tool, all of the power feed breakers trip. They use 24VDC because they have a battery backed 24VDC power supply to feed it so they can energize it initially.

 

[Cold Fusion]

Square D:
field installed #S29410 for their new H and J frame breakers
factory installed suffix # -1143 for their traditional line of breakers

You're right. I looked up SQD FA and they do offer UV trips down to 6VDC.

Done all the time in the semiconductor tooling industry. They use 24VDC in what they call the "EMO" circuit (EMergency Off) where if someone slaps a mushroom head EMO button anywhere on the tool, all of the power feed breakers trip. They use 24VDC because they have a battery backed 24VDC power supply to feed it so they can energize it initially.

Thanks - I couldn't see any use for a 480V CB with a 24VDC UV trip.

Curious design philosophy. Makes one wonder what is special about that industry.

Just curious:
Is this "done all the time" on molded case, insulated case, metal clad, or all three?

This "semiconductor tooling industry", is that making semiconductors or making tooking that makes semiconductors?

I wonder what the 6VDC UV trips are used for?

cf

 

[ELA]

Thanks - I couldn't see any use for a 480V CB with a 24VDC UV trip.

Curious design philosophy. Makes one wonder what is special about that industry.


This "semiconductor tooling industry", is that making semiconductors or making tooking that makes semiconductors?



cf

One reason that some Semiconductor processing equipment (equipment used in manufacturing of the IC chips) uses DC voltage for EMO circuits is to meet the specific set of standards that apply to that industry.
In this case SEMI F47. This standard requires the equipment to "ride out" short brownouts. A lot of equipment manufacturers had trouble meeting this standard when it was first introduced. One solution was to use dc power to the EMO coils/circuits.

http://f47testing.epri.com/f47abstract.html

Prior to F47 we used UV trips, afterwords we changed to DC powered safety relays to power the main contactors coils.

 

[Cold Fusion]

One reason that some Semiconductor processing equipment (equipment used in manufacturing of the IC chips) uses DC voltage for EMO circuits is to meet the specific set of standards that apply to that industry.
In this case SEMI F47. This standard requires the equipment to "ride out" short brownouts. A lot of equipment manufacturers had trouble meeting this standard when it was first introduced. One solution was to use dc power to the EMO coils/circuits.

http://f47testing.epri.com/f47abstract.html

Prior to F47 we used UV trips, afterwords we changed to DC powered safety relays to power the main contactors coils.

I read through the abstract and did not see any thing special. Most of the stuff I work with meets that - except I can't tell about the motors and motor contactors. For control systems, the methods I generally work with involve UPS systems. As for the motors and contactors - If the power quits for a few cycles or more, the contactors drop out and generally stay out until the power is restored and then restarted in an orderly manner. The control systems are fed from UPSs and stay functional.

Are you saying in the event of a power failure, the intent is to keep the motor contactors pulled in even though the power to the motors is gone? Even more curious. Probably more that is not in the abstract.

cf

 

[Jraef]

I read through the abstract and did not see any thing special. Most of the stuff I work with meets that - except I can't tell about the motors and motor contactors. For control systems, the methods I generally work with involve UPS systems. As for the motors and contactors - If the power quits for a few cycles or more, the contactors drop out and generally stay out until the power is restored and then restarted in an orderly manner. The control systems are fed from UPSs and stay functional.

Are you saying in the event of a power failure, the intent is to keep the motor contactors pulled in even though the power to the motors is gone? Even more curious. Probably more that is not in the abstract.

cf

Generally, the semiconductor tooling this refers to does not have a lot of motors. They are dealing with highly toxic gasses controlled by solenoid valves and extreme temperatures controlled by electric heating (i.e. 2000 degrees etc.). Short duration brownouts and control power losses can have incredibly disastrous consequences by virtue of the control system losing control when power immediately comes back on, not only in lost revenue but also in risks to employees from exposure to uncontrolled hazmats. But when something goes completely haywire, the EMO circuit must operate to completely kill power without allowing it t come back on, i.e. opening a circuit breaker. They can use contactors as well, it's just that some engineers prefer it one way or the other.

 

[ELA]

I read through the abstract and did not see any thing special.

Are you saying in the event of a power failure, the intent is to keep the motor contactors pulled in even though the power to the motors is gone?

cf

To make the comment you did I assume your equipment has been tested to the levels prescribed in the link?
Many people "thought" their equipment would meet these requirements and were surprised to find out that they didn't once they actually performed the required testing.

The comments were about an EMO circuit. If the the contactors coil current cannot hold up for the amount of time prescribed in the standard then the tool would EMO during the brownout/complete outage and this was not allowed.
This is a minimum standard for this particular Industry. Manufacturers such as Samsung have an even more stringent requirement called "power Vaccine".

Read deeper if you are more curious.

http://powerstandards.com/

http://www.powermag.com/o_and_m/

http://findarticles.com/p/articles/mi_qa5392/is_200801/ai_n25137622/

 

[Cold Fusion]

To make the comment you did I assume your equipment has been tested to the levels prescribed in the link?
Many people "thought" their equipment would meet these requirements and were surprised to find out that they didn't once they actually performed the required testing. ---

Well, I'm somewhat familiar with safety related control systems rated SIL4. That is a pretty stringent standard - but it's a different animal than the one you are discussing here.

Mostly I'm interested in what is different about industries that use UV CBs as E-stops. I've been hanging around electrical controls in industry for 40 years and I've not seen that in pulp and paper, refining, pipeline, nuc propulsion, or small generation - not in process control or fire protection/suppression.

So, I'm wondering what is so different about semiconductor mfg that pushes designers to using this type of cb for estop control?

It's not bad, just different and I'm curious why. I'll get a chance next week to look at your other sources - maybe they will shed some light.

cf

 

[Cold Fusion]

Generally, the semiconductor tooling this refers to does not have a lot of motors. They are dealing with highly toxic gasses controlled by solenoid valves and extreme temperatures controlled by electric heating (i.e. 2000 degrees etc.). Short duration brownouts and control power losses can have incredibly disastrous consequences by virtue of the control system losing control when power immediately comes back on, not only in lost revenue but also in risks to employees from exposure to uncontrolled hazmats. But when something goes completely haywire, the EMO circuit must operate to completely kill power without allowing it t come back on, i.e. opening a circuit breaker. They can use contactors as well, it's just that some engineers prefer it one way or the other.

Doesn't sound any worse than either the nuc plants or the refineries i've worked. What, these guys have never heard of UPSs, spinning reserve, fail-to-safe-position valves? I suspect they have and it isn't that. If I had to guess, I'd guess lost revenue is the driver. Which is easy for me to say - that's generally the driver in all industry.

cf

 

[ELA]

Mostly I'm interested in what is different about industries that use UV CBs as E-stops.

So, I'm wondering what is so different about semiconductor mfg that pushes designers to using this type of cb for estop control?

cf

I am not so sure it is industry driven to use one particular method for removing power. As Jraef mentioned some use UV breakers and some use contactors.
More recently safety relays have become more common for the increased safety levels they can provide.

 

[Cold Fusion]

---More recently safety relays have become more common for the increased safety levels they can provide.

I'm not familiar with the term, 'safety relay'. What is that? And could you give some context?

cf

 

[ELA]

http://www.pilz.com/products/control_communication/safety_relay/sub/benefits/index.en.jsp


We used the Pilz relays.
They are used for many different reasons. They make interfacing various safety oriented euipment into a system a bit easier while providing a higher level of safety.
The inputs monitor EMO pushbuttons and outputs can drive contactors etc.