My 480 V to 48vdc field power supplies were blowing when I press estop. I put a power analyzer is my main feed to measure voltage and current . I see a 200 Amps spike when pressing estop. I checked all the installations and they all look good. This is a conveyor systems . What will be the possible source of this 200 Amps spike that comes when I press estop?
200 Amps current spike when pressing estop
- Thread starter RNLENI
- Start date
- Status
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
210617-1515 edt
RNLENI:
You are going to have to provide much more clarity to your question.
What is a "48 V DC field power supply"? Is this the supply to the field coils of DC motors?
What was "blowing"? What does blowing mean?
Where is the 200 A spike measured?
Provide a circuit diagram of your circuit.
What does "I checked all the installations and they all look good." mean? What is an "installation"?
Where is "Estop" located in the circuit? And what does it do?
What is the normal running current at the location you see the 200 A spike?
Are the loads DC motors or what?
What does "field power" mean? If it is power to the field coils of DC motors, and you are interrupting this current, then you have energy stored in those field coils. Upon opening such a circuit the current will continue unchanged for a moment, then gradually drop, and produce an arc across the switch contacts to maintain current flow. This does not provide an increase in current at the contact. However, a large voltage is generated to produce the the spark or arc. An arc voltage drop is a much lower voltage, possibly 10 to 50 V, than a spark voltage drop, possibly a 1000 V or higher.
Are you really an engineer? I would expect an engineer to more clearly describe the circuit, and details of the problem?
.
RNLENI:
You are going to have to provide much more clarity to your question.
What is a "48 V DC field power supply"? Is this the supply to the field coils of DC motors?
What was "blowing"? What does blowing mean?
Where is the 200 A spike measured?
Provide a circuit diagram of your circuit.
What does "I checked all the installations and they all look good." mean? What is an "installation"?
Where is "Estop" located in the circuit? And what does it do?
What is the normal running current at the location you see the 200 A spike?
Are the loads DC motors or what?
What does "field power" mean? If it is power to the field coils of DC motors, and you are interrupting this current, then you have energy stored in those field coils. Upon opening such a circuit the current will continue unchanged for a moment, then gradually drop, and produce an arc across the switch contacts to maintain current flow. This does not provide an increase in current at the contact. However, a large voltage is generated to produce the the spark or arc. An arc voltage drop is a much lower voltage, possibly 10 to 50 V, than a spark voltage drop, possibly a 1000 V or higher.
Are you really an engineer? I would expect an engineer to more clearly describe the circuit, and details of the problem?
.
synchro
Senior Member
- Location
- Chicago, IL
- Occupation
- EE
I assume that this issue is the same as the one from your previous post linked below where you said:
Are the power supplies being fed with 480V L-L or with 277V L-N?
When you used the power analyzer did you measure the L-G, or the N-G voltage if you have a neutral conductor? Perhaps the neutral terminal of a transformer wye secondary that's providing the 480V is not adequately bonded to equipment ground. If so then L-G voltages might have an overvoltage during switching events which then causes your observed failures. In that case surge suppresion devices might be producing current spikes and may be failing.
...
48VDC FIELD POWER SUPPLIES BLOWS OFF
I have 480VAC 3ph 60hz Power buses going out from my main cabinet to field. Each Buses are on different contactors and feeds certain number of 48VDC Power supplies. The 48VDC supply feed my conveyor rollers. Its noticed that when I operate the Estop , some times these 48VDC Power supplies blows...
forums.mikeholt.com
Are the power supplies being fed with 480V L-L or with 277V L-N?
When you used the power analyzer did you measure the L-G, or the N-G voltage if you have a neutral conductor? Perhaps the neutral terminal of a transformer wye secondary that's providing the 480V is not adequately bonded to equipment ground. If so then L-G voltages might have an overvoltage during switching events which then causes your observed failures. In that case surge suppresion devices might be producing current spikes and may be failing.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
Is this a problem on a machine being commissioned or is this a problem that has developed on a machine that was operating fine?
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
48VDC for the ROLLERS? Or 48VDC for BRAKES on the conveyor? Solenoid brakes are typically spring loaded, held open (released) so they will engage the brake when power is cut. That will give an inductive voltage kickback spike when released, but not current. to oldspark’s point if it was working fine and now has issues, there may have been surge suppressors on the solenoids that have now failed. They get old and burn out.
If the solenoid brakes are ENGAGED when you hit the E-Stop, there would be a big current spike to energize the coils.
If the solenoid brakes are ENGAGED when you hit the E-Stop, there would be a big current spike to energize the coils.
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