Trip Relay Light

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hawkeye23

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stanton
Yesterday when replacing some bulbs on the switchgear that indicate if breaker is open or closed i notice the digatrip had a flashing red lite on the ground fault indicator and though the breaker should have tripped open . I have seen a flag on a trip unit before which showed a fault and the breaker never opened because of poor maintenance and this seems to be the same situation.

Does anyone have an idea if this breaker should have opened on the indicating ground fault light ?
 
Need more data

Need more data

I am not familiar with "digatrip" but that light may means something other than ground fault. Perhaps it means bad sensor? Do you have the manual?
 
Manual

Manual

The Square D Digitrip instruction manual says that a flashing green light indicates the trip unit is functional.

"Time-current curves are depicted on the face of the trip unit. After an
automatic trip, the reason for the trip is identified by the segment of the timecurrent
curve where the LED illuminates (Figure 5 on page 9). A backup
battery continues to supply power to the LEDs after an automatic trip.
A green Unit Status LED (Figure 5 on page 9) indicates the operational status
of the trip unit. Once the load current through the circuit breaker exceeds
approximately 10% of the frame/current sensor rating, the LED flashes once
each second, indicating that the trip unit is energized and operating properly.
If the LED stays on steadily (does not flash), the trip unit is not ready to
perform its circuit protective functions. If the LED continues to stay on
steadily, check the trip unit for proper operation."
 
hawkeye23 said:
Yesterday when replacing some bulbs on the switchgear that indicate if breaker is open or closed i notice the digatrip had a flashing red lite on the ground fault indicator and though the breaker should have tripped open . I have seen a flag on a trip unit before which showed a fault and the breaker never opened because of poor maintenance and this seems to be the same situation.

Does anyone have an idea if this breaker should have opened on the indicating ground fault light ?
Click to expand...

Yes, it should have tripped, it is possible it did trip and someone re-closed the breaker without resetting the targets. (Red light)
 
We have flashing geen status light and a solid red light on the ground fault pickup "d" or ground fault time ".3" not sure how to read this.
Thanks for the help here.
 
hawkeye23 said:
We have flashing geen status light and a solid red light on the ground fault pickup "d" or ground fault time ".3" not sure how to read this.
Thanks for the help here.
Click to expand...

That is just telling you there was a GF trip signal, the pickup value is just the setting. Depending on what version of digitrip you have there may be a trip history and/or fault code you can pull up for more info.
 
hawkeye23 said:
We have flashing geen status light and a solid red light on the ground fault pickup "d" or ground fault time ".3" not sure how to read this.
Thanks for the help here.
Click to expand...

D is the current setting and is dictated by the circuit breaker size, this information is sometimes on the side of the CB, otherwise you need to get the instruction manual out. The .3 is the try delay .3 seconds.
 
Digitrp RMS 510 Trip Unit

Digitrp RMS 510 Trip Unit

hawkeye23 said:
Yesterday when replacing some bulbs on the switchgear that indicate if breaker is open or closed i notice the digatrip had a flashing red lite on the ground fault indicator and though the breaker should have tripped open . I have seen a flag on a trip unit before which showed a fault and the breaker never opened because of poor maintenance and this seems to be the same situation.

Does anyone have an idea if this breaker should have opened on the indicating ground fault light ?
Click to expand...

Several years ago I was called out on a similar situation. Below is an excerpt from the field service report. Although the trip unit tested ok on the self-test, we concluded that it was a nuisance indication and ended up replacing the trip unit.

1. ApparatusIdentification 2. Time In/Type of Service 3. Scope of Work to be performed 4. As Found Conditions 5. Work Done and Status of Job 6. Results & Recommendations

1. HSP, I.E.M. 4000A, 480/277V, 3-Phase, 4-Wire, S.O. 046186-001, Main Breaker ?Commercial Breaker #2?, Cutler-Hammer, SPB-100 Insulated Case Circuit Breaker, Cat# SPBR340R, 4000A Frame, with Digitrip 510 Trip Unit Cat# S56LSIG(D), 4000A Plug, Cat# RP6S40A400, In = 4000A.
2. Six years/ charge customer.
3. Investigate the Ground Fault Trip Light indication on the ?Commercial Breaker #2? Main Breaker.
4. BACKGROUND:
Customer reported that during a walk thru on the previous day he noticed the Ground Fault Trip LED indication on the ?Commercial Breaker #2? Main Breaker.
There was no recollection that the breaker had tripped.

5. WORK DONE:
? The Main Breaker was inspected and the Ground Fault Trip LED was found lit with the breaker closed.
? The customer was asked if there were any 277V lighting circuits fed from this breaker and if there was any recent work done on these circuits. He indicated that there was work done on the lighting but was not sure if it was fed by this breaker.

JOB STATUS:
The Ground Fault Trip LED will be reset after a time can be scheduled to properly test the Main Breaker trip unit to determine its integrity.


6. CONCLUSIONS and RECOMMENDATIONS:
? The Main Breaker trip unit has the following trip functions:
1. Long Time Delay
2. Short Time Delay
3. Instantaneous
4. Ground Fault
In the event that the breaker trips on a fault, one of the above LEDs lights to indicate the type of fault that caused the trip. In this case the Ground Fault LED lit but the breaker did not trip. This is an indication that the trip unit may be defective. Another possibility is that the trip unit sensed a ground
fault on the system but did not trip the breaker. A third possibility is that the LED indication is a result of the last self test performed over a year ago and was never reset. In any case, SFE recommends the following:
1. Order a new trip unit.
2. Schedule a time whereby the load fed from this breaker can be transferred to the generator and perform a self test on the trip unit. Based on the results of the test it could be determined if the trip unit needs to be replaced.
 
Wow! Just wow. You had them replace the trip unit becuase the light was on?

A "self test" tells you little about the functionality of the trip unit, to determine if it is operating it need to be tested by inputing test currents for each trip fucntion and comparing trip times to the curves. However, all of that is moot, if the red light is on the GF a trip signal was fired by the trip unit so I highly doubt there is anything at aall wrong with the trip unit. But there is a very good chance there is an issue with the trip actuator, most common issue on these breakers it the actuator is not fully reset (Improper adjustment) so it won't fire when it get the trip signal from the trip unit. This can be a dangerous condition, it means the plant lost all protection on this circuit.

I would have a testing company come out there ASAP and test that breaker properly.
 
Nuisance Indications/ Nuisance Trips

Nuisance Indications/ Nuisance Trips

zog said:
Wow! Just wow. You had them replace the trip unit becuase the light was on?

[U]A "self test" tells you little about the functionality of the trip unit, to determine if it is operating it need to be tested by inputing test currents for each trip fucntion and comparing trip times to the curves.[/U] However, all of that is moot, if the red light is on the GF a trip signal was fired by the trip unit so I highly doubt there is anything at aall wrong with the trip unit. But there is a very good chance there is an issue with the trip actuator, most common issue on these breakers it the actuator is not fully reset (Improper adjustment) so it won't fire when it get the trip signal from the trip unit. This can be a dangerous condition, it means the plant lost all protection on this circuit.

I would have a testing company come out there ASAP and test that breaker properly.
Click to expand...

The issue here is whether the trip unit sensing circuit sensed an actual GF signal, triggered the red LED indication but the breaker did not trip (actuator problem) OR there was no GF on the system, the trip unit sent a false LED indication but did not send a signal to trip the breaker(defective trip unit.) This was stated in my opening reply.
By "inputting test currents" I will assume you mean High Current Testing (primary injection.)
A test whether it be primary injection or secondary injection(self-test) only proves the functionality of the trip unit and that the breaker will trip. It will not prove that the trip unit will NOT send a false (nuisance) indication. The only solution was to replace the trip unit and test the functionality and actuator trip. We chose the self-test over primary injection due to the high cost of bringing in the big test sets.
The self-test is a perfectly valid test to prove the solid state logic and actuator functions. It does not prove the integrity of the phase sensing CTs which are usually tested during commissioning. Refer to the following C-H instruction leaflets for verification of self testing with the APM power module: I.L. 29-885, P. 12 thru 14, I.L. 29-849A, P. 4
The trip unit was replaced, tested and the breaker has not had any problems since it was done 7 years ago. This is further proof that the diagnosis was correct and there was no GF on the system. The GF indication was false and the trip unit was defective.

We find this to be a common problem especially with solid state components built in the 70's and 80's: protective relays, external GF relays, trip units in MCCBs, etc. The electrolytic capacitors (in the power supplies) used back then begin to fail causing misfiring resulting in all kinds of havoc.

Have you ever experienced nuisance tripping of devices in the field? I am surprised with all your experience that you did not consider this a possibility when you wrote your reply.:?
 
ATSman said:
Have you ever experienced nuisance tripping of devices in the field? I am surprised with all your experience that you did not consider this a possibility when you wrote your reply.:?
Click to expand...

Get calls for that all the time, 99% of the time we can find out what the cause was without making assumptions.
 
Thank you guys for all the great responses to our post . We opened the circuit breaker today [just got permission today] and hit the reset on the trip relay and then closed the breaker , light gone everything seems fine now. The only led is the flashing green .

The only red led to come on was the gf time set .3 , the gf pickup led never came on that we know. We always had a flashing green led on all the time with the red led.

All great information and help from you all, thanks.
 
hawkeye23 said:
Thank you guys for all the great responses to our post . We opened the circuit breaker today [just got permission today] and hit the reset on the trip relay and then closed the breaker , light gone everything seems fine now. The only led is the flashing green .

The only red led to come on was the gf time set .3 , the gf pickup led never came on that we know. We always had a flashing green led on all the time with the red led.

All great information and help from you all, thanks.
Click to expand...

I would still have the breaker tested to be sure it functions properly, either it failed to trip or someone didn't fess up to reseting it without telling anyone.

Or just randomly replace the trip unit and claim you solved the problem
 
ATSman said:
A test whether it be primary injection or secondary injection(self-test) only proves the functionality of the trip unit and that the breaker will trip. It will not prove that the trip unit will NOT send a false (nuisance) indication. The only solution was to replace the trip unit and test the functionality and actuator trip. We chose the self-test over primary injection due to the high cost of bringing in the big test sets.
The self-test is a perfectly valid test to prove the solid state logic and actuator functions. It does not prove the integrity of the phase sensing CTs which are usually tested during commissioning. Refer to the following C-H instruction leaflets for verification of self testing with the APM power module: I.L. 29-885, P. 12 thru 14, I.L. 29-849A, P. 4
The trip unit was replaced, tested and the breaker has not had any problems since it was done 7 years ago. This is further proof that the diagnosis was correct and there was no GF on the system. The GF indication was false and the trip unit was defective.
Click to expand...

Let me get this straight, you decided not to test the trip unit via primary injection due to the "high cost" of bringing in test equipment but you replaced the trip unit (At a much higher cost) and then had it tested anyways (Same "high cost")? Don't see how you justify any cost savings here or how you can call your diagnosis"proof" of being correct, what exactly did you prove? Proof would suggest you found a defective compoenent in the trip unit, which you never tested?
 
zog said:
Let me get this straight, you decided not to test the trip unit via primary injection due to the "high cost" of bringing in test equipment but you replaced the trip unit (At a much higher cost) and then had it tested anyways (Same "high cost")? Don't see how you justify any cost savings here or how you can call your diagnosis"proof" of being correct, what exactly did you prove? Proof would suggest you found a defective compoenent in the trip unit, which you never tested?
Click to expand...

The self-test is a perfectly valid test to prove the solid state logic and actuator functions. Although it is a Go - No Go test, it proves the function of each trip parameter the same as primary injection. Please read the manufacturers instruction manuals I mentioned. I can send copies if you need them. It is time that you educate yourself and really understand how these devices work. This is not hearsay, this is direct from Cutler-Hammer (Eaton.)
I don't know what your labor rates are in N.C. but the cost of the trip unit here is peanuts compared to a two man team with a high current test set for a full shift on overtime. As I stated before: A test whether it be primary injection or secondary injection(self-test) only proves the functionality of the trip unit and that the breaker will trip. It will not prove that the trip unit will NOT send a false (nuisance) indication. In this case, the only way to prove that the part was defective is to replace it and self-test it for functionality. If there are no further nuisance indications (LED lit and no trip) then it can only be concluded that the part was defective. I don't know how much plainer I can explain myself.
Zog, If we are to continue this discussion please stick with the facts and not with "I still think" without any thing to back it up with. Thanks.
 
I am very familiar with these trip units, don't need you to send anything but if you read the inst book it says the self test is a functional test only and not a calibration test.

Proof would mean you were able to re-create the conditions that cause the "false trip" to occur, don't see how you proved anything, just that the same issue has not occured again. There may have been an actual ground fault and either the breaker failed to trip or someone reset it without telling anyone. Or if this is set up as a 3 wire configuration there may have been unbalanced phase loading with will often give you a false ground fault trip. All unanswered questions until you prove the trip unit was faulty with a root cause analysis.
 
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