Hi, I have a 230V Power DB which is feeding the 230V control supply to PLC panel. The outgoing power circuits of this Power DB is equiped with MCB (6A) and RCCB (300mA). Today I noticed that the MCB tripped in the circuit which feeding to PLC control supply mentioned above. Please clarify why RCCB not done anything?
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MCB tripped but RCCB not tripped 2
- Thread starter Histor
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2
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RCCB gets trip when there is a ground fault or earth leakage fault. In the case of a short circuit or overcurrent, the MCB will trip. If you want to have both types of protection with one device, install RCBO ( Residual current circuit Breaker)- it will trip in the case of overcurrent, short circuit, and earth leakage.
If you are feeding more control devices than just the PLC, look for a failed or failing control device or damaged wiring.
Check your circuits for circuit race.
Check for opposite polarity applications of NO/NC, three pole contacts.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Check your circuits for circuit race.
Check for opposite polarity applications of NO/NC, three pole contacts.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Inductive field devices may have an energization surge sufficient to trip a 6 Amp breaker.
Enegization surge depends on both residual magnetism in a dvice and on the point on wave when the potential is applied.
A circuit may work well for a long time and then unexpectedly fail.
The circuit may then work well for an unknown length of time until it fails again.
The energization surge of some transformers may be as high as 2500% of rated current.
The solution?
A dual element or Slo-Blo fuse.
Possibly a 12 Amp Slo-Blo fuse.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Enegization surge depends on both residual magnetism in a dvice and on the point on wave when the potential is applied.
A circuit may work well for a long time and then unexpectedly fail.
The circuit may then work well for an unknown length of time until it fails again.
The energization surge of some transformers may be as high as 2500% of rated current.
The solution?
A dual element or Slo-Blo fuse.
Possibly a 12 Amp Slo-Blo fuse.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Mr. Histor (Electrical)(OP)28 May 23 12:34
"....I have a 230V Power DB which is feeding the 230V control supply to PLC panel. The outgoing power circuits of this Power DB is equiped with MCB (6A) and RCCB (300mA). Today I noticed that the MCB tripped in the circuit which feeding to PLC control supply mentioned above. Please clarify why RCCB not done anything?"
I fully agreed with the advice by learned Mr.Pandit1.
I wish to add a little information for your consideration:
1. RCCB (300mA) may trips from >150mA on Earth fault only. It does NOT trip on over-current or short circuit current, up to any level.
2. A thermal magnetic MCB (6A) trips on thermal effect at any current > 6A with an inverse time delay, i.e. the higher the current, shorter the tripping time. The magnetic instantaneous trip depending on the tripping characteristics (i.e. B[3-5], C[5-10], D[10-20] times for the rated current) e.g. a 6A MCB with characteristic C would trip instantaneously between (5x6A) to (10x6A); otherwise characteristic D would be fine for most applications.
3. MCB is preferred instead of any type of fuses. In most cases, a 10kA MCB can switch back the supply immediately after the fault is rectified. In most cases, there is NO damage to the MCB.
Che Kuan Yau (Singapore)
"....I have a 230V Power DB which is feeding the 230V control supply to PLC panel. The outgoing power circuits of this Power DB is equiped with MCB (6A) and RCCB (300mA). Today I noticed that the MCB tripped in the circuit which feeding to PLC control supply mentioned above. Please clarify why RCCB not done anything?"
I fully agreed with the advice by learned Mr.Pandit1.
I wish to add a little information for your consideration:
1. RCCB (300mA) may trips from >150mA on Earth fault only. It does NOT trip on over-current or short circuit current, up to any level.
2. A thermal magnetic MCB (6A) trips on thermal effect at any current > 6A with an inverse time delay, i.e. the higher the current, shorter the tripping time. The magnetic instantaneous trip depending on the tripping characteristics (i.e. B[3-5], C[5-10], D[10-20] times for the rated current) e.g. a 6A MCB with characteristic C would trip instantaneously between (5x6A) to (10x6A); otherwise characteristic D would be fine for most applications.
3. MCB is preferred instead of any type of fuses. In most cases, a 10kA MCB can switch back the supply immediately after the fault is rectified. In most cases, there is NO damage to the MCB.
Che Kuan Yau (Singapore)
The circuit breaker trips on any over current.
The RCCB only trips on unbalanced current.
A surge or a device shorted or partially shorted internally will trip the circuit breaker on balanced over-current.
If a device shorts to ground, the RCCB will trip.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
The RCCB only trips on unbalanced current.
A surge or a device shorted or partially shorted internally will trip the circuit breaker on balanced over-current.
If a device shorts to ground, the RCCB will trip.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
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