Characteristics
Characteristics
Characteristics
The most widely used are 30 mA (milliamp) and 100 mA devices. A current flow of 30 mA (or 0.03 amps) is sufficiently small that it makes it very difficult to receive a dangerous shock. Even 100 mA is a relatively small figure when compared to the current that may flow in an earth fault without such protection (hundred of amps)
A 300/500 mA RCCB may be used where only fire protection is required. eg., on lighting circuits, where the risk of electric shock is small.
1 : ACB by definition is Air Circuit Breaker - which means, the air gap developed in between the fixed & movable contacts act as insulation. However, the use of such circuit breaker is not much nowadays due to various drawbacks.
2 : MCCB by definition is Miniature Coil Circuit breaker. The contacts are released with the application of desired voltage to the coil controlling the movement of the contacts.
MCCB (Moulded Case Circuit Breaker)
Characteristics
Rated current up to 1000 A.
Trip current may be adjustable.
Thermal or thermal-magnetic operation.
RCCB(Residual Current Circuit Breaker)
Characteristics
Phase (line) and Neutral both wires connected through RCD.
It trips the circuit when there is earth fault current.
The amount of current flows through the phase (line) should return through neutral .
It detects by RCD. any mismatch between two currents flowing through phase and neutral detect by -RCD and trip the circuit within 30Miliseconed.
If a house has an earth system connected to an earth rod and not the main incoming cable, then it must have all circuits protected by an RCD (because u mite not be able to get enough fault current to trip a MCB)
shunt trip coil used to trip the breaker automatically or manually.
The door interlock prevents the switchboard door from being opened unless the breaker body is in the ISOLATED position. Only when the draw-out handle is removed from the ACB when the ACB is in the ISOLATED position, is the door interlock released and the switchboard door allowed to open. When inserting the ACB back into the carriage, the switchboard door must be closed once the breaker is in the ISOLATED position. When the door interlock is supplied a special draw-out handle is also supplied.
Indian Standard Specification for LT switchgear and ControlgearIS 13947-1 General requirements of switchgear and controlgear for voltage not exceeding 1000 V ac.IS 13947-2 LV Circuit breaker ( ACB/MCB/MCCB/RCB ) for voltage not exceeding 1000 V ac or 1200 V dc.IS 13947-3 Air- Break switches, Air-Break disconnector and fuse combination unit for voltage not exceeding 1000 V ac or 1200 V dc.IS 13947-4 Contractors and motor starters.IS 13947-5 Control circuit devices and switching elements.IS 8623-3 Specification for factory built assemblies of switchgear and controlgear for voltage uptoand including 1000 V ac and 1200 V dc.IS 10118-4 Code for practice for selection installation and maintenance of conductors and apparatus terminals.IS 12021 Specification of control transformers for switchgear and controlgear for voltage not exceeding 1000 V ac.IS 11353 Guide for uniform systems of making and identification of conductors.IS 3043 Code of practice for earthing.IS 3072 Code of practice for installation and maintenance of switchgear.IS 3231 Electrical Relays for power system protection.
The importance of phase sequence is related to the direction of rotation for a motor. The three phases set up a rotating magnetic field, which runs the motor. Reverse the sequence, and most motors will run backwards, not necessarily a good thing. There really are only two sequences; ABC, and ACB. All other sequences are permutations of one of these.
there is three difference in ACB and MCCB, 1- ACB on off operation is easy as com pair to mccb because acb having charged spring force. 2- acb having much delay time period (category A) and mccb having low time period (category B) 3- the main diffidence is that acb having high raptching capacity and mccb are low.
vcb and acb
thokka thotakoora
VCB (vacuum circuit breaker) is used in HV (high voltage) applications. ACB (air circuit breaker) is used in LV (low votage) applications.
Electrical maintenance is used for maintenance of electrical equipment. Electrical Preventive Maintenance is been used for replacement of Low voltage distribution products such as ACB's & MCCB's Contactors and Relays.
Arc developed during closing/opening operation is extinguished by air in ACB and by oil in OCB
Liga ACB was created in 1957.
College ACB was created in 2008.
ACB Lagos ended in 1994.
false
The length of arc ACB is 57.2.
FALSE