What is the difference between a contactor and a breaker?

What is the difference between a contactor and a breaker?
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1 Answer

Answer :

Contactor is not designed to open on short circuit condition (fuse will take care of this situation). Breaker is having complicated mechanism for closing and tripping. 
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Related questions

Which of the following statements represents the main difference between a relay and a contactor? A. Contactors control current and relays control voltage. B. A relay is series connected and a contactor is parallel connected. C. Contactors can handle heavier loads than relays. D. Contactors are made from silver and relays are made from copper.

Description : Which of the following statements represents the main difference between a relay and a contactor? A. Contactors control current and relays control voltage. B. A relay is series connected and a contactor ... loads than relays. D. Contactors are made from silver and relays are made from copper.

Last Answer : Answer: C

What is the difference between isolator and contactor?

Description : What is the difference between isolator and contactor?

Last Answer : Contactor is used for on load operation. Because they are fast acting devices. They posses arc chamber and arc chutes. Arc chamber and arc chute make it easy to extinguish the arc produced during on ... acting devices. The arc time is more in slow acting devices and operated only in off load. 

In the illustration shown, coil 'MR' is a ____________. EL-0012 A. running contactor coil B. rupture (blowout) coil C. resistance coil D. reversing coil

Description : In the illustration shown, coil 'MR' is a ____________. EL-0012 A. running contactor coil B. rupture (blowout) coil C. resistance coil D. reversing coil

Last Answer : Answer: A

Which component is responsible for energizing solenoid 'B1-B2' and releasing the brake for the winch motor shown in the illustration? EL-0102 A. Contactor '3M' B. A spring not shown in the schematic diagram C. Resistor 'B2-R1' D. Relay 'FR-B.O.'

Description : Which component is responsible for energizing solenoid 'B1-B2' and releasing the brake for the winch motor shown in the illustration? EL-0102 A. Contactor '3M' B. A spring not shown in the schematic diagram C. Resistor 'B2-R1' D. Relay 'FR-B.O.'

Last Answer : Answer: A

The winch shown in the illustration will not operate in any speed in the lowering direction and at an abnormal speed in 'first point hoist'. The possible cause is that _______________. EL-0102 A. contactor coil '3M' has many shorted turns B. resistor 'R8-A2' has an open C. contacts '1M' in the power circuit are badly corroded D. master switch contacts 'MS6' have weak springs

Description : The winch shown in the illustration will not operate in any speed in the lowering direction and at an abnormal speed in 'first point hoist'. The possible cause is that _______________. EL-0102 A. ... '1M' in the power circuit are badly corroded D. master switch contacts 'MS6' have weak springs

Last Answer : Answer: B

The winch shown in the illustration operates in any of the positions with the master switch in the 'lower' direction, but will not 'hoist' in any of the master switch hoist positions. Which of the listed faults could be the cause? EL-0102 A. Master switch contact 'MS3' may have defective springs. B. Contactor '3M' coil could have an open winding. C. Contact '2M' in the power circuit may be badly corroded. D. Series relay 'FR' may be open.

Description : The winch shown in the illustration operates in any of the positions with the master switch in the 'lower' direction, but will not 'hoist' in any of the master switch hoist positions. Which of the listed faults ... '2M' in the power circuit may be badly corroded. D. Series relay 'FR' may be open.

Last Answer : Answer: A

The illustrated motor fails to start and gives a loud hum when the start button is depressed, your first action should be to __________. EL-0007 A. disassemble the motor to fix the centrifical switch so the start windings will be energized B. push the stop button to deenergize the 'M' coil C. reset the thermal overload D. hold the 'M' contactor closed by hand while wearing electrical safety gloves to get motor started

Description : The illustrated motor fails to start and gives a loud hum when the start button is depressed, your first action should be to __________. EL-0007 A. disassemble the motor to fix the centrifical ... D. hold the 'M' contactor closed by hand while wearing electrical safety gloves to get motor started

Last Answer : Answer: B

If many turns of an alternating current coil for a contactor become short circuited, the coil _____________. A. will continue to operate B. will probably burn out immediately C. will operate on reduced current D. temperature will drop

Description : If many turns of an alternating current coil for a contactor become short circuited, the coil _____________. A. will continue to operate B. will probably burn out immediately C. will operate on reduced current D. temperature will drop

Last Answer : Answer: B

The heaters for the winch circuit shown in the illustration are powered from _____________. EL-0102 A. a separate source B. the winch main bus C. the master switch power circuit D. the contactor control circuit

Description : The heaters for the winch circuit shown in the illustration are powered from _____________. EL-0102 A. a separate source B. the winch main bus C. the master switch power circuit D. the contactor control circuit

Last Answer : Answer: A

When troubleshooting motor controllers, a shorted relay or contactor coil is often indicated by _______________. A. a resistance reading of 'infinity' on an ohmmeter B. charred insulation and/or a blown control fuse C. a reading of 'zero' on a megger from one of the coil's leads to ground D. a higher-than-normal voltage reading across the winding

Description : When troubleshooting motor controllers, a shorted relay or contactor coil is often indicated by _______________. A. a resistance reading of 'infinity' on an ohmmeter B. charred insulation and/or a blown ... of the coil's leads to ground D. a higher-than-normal voltage reading across the winding

Last Answer : Answer: B

The 'safe switch' of the winch controller shown in the illustration is operated _______________. EL-0102 A. through the master switch handle B. when heater circuit current is high C. by contactor coil 'FR' D. manually by the winch operator

Description : The 'safe switch' of the winch controller shown in the illustration is operated _______________. EL-0102 A. through the master switch handle B. when heater circuit current is high C. by contactor coil 'FR' D. manually by the winch operator

Last Answer : Answer: D

If a magnetic controller contactor fails to pick up when the coil voltage is applied to the contactor coil, the cause may be _____________. A. overload B. misalignment of the affected contactor contacts C. low spring pressure D. an open contactor coil

Description : If a magnetic controller contactor fails to pick up when the coil voltage is applied to the contactor coil, the cause may be _____________. A. overload B. misalignment of the affected contactor contacts C. low spring pressure D. an open contactor coil

Last Answer : Answer: D

If many turns of an alternating current coil for a contactor become short circuited, the coil _____________. A. temperature will drop B. will probably burn out immediately C. will continue to operate D. will operate on reduced current

Description : If many turns of an alternating current coil for a contactor become short circuited, the coil _____________. A. temperature will drop B. will probably burn out immediately C. will continue to operate D. will operate on reduced current

Last Answer : Answer: B

Magnet chatter or 'pumping' occurring in a magnetic contactor can be caused by ______________. A. dirt or grease on pole faces B. mechanical interference in the contacts C. chattering contacts on the control relay D. magnetic lock out of the contacts

Description : Magnet chatter or 'pumping' occurring in a magnetic contactor can be caused by ______________. A. dirt or grease on pole faces B. mechanical interference in the contacts C. chattering contacts on the control relay D. magnetic lock out of the contacts

Last Answer : Answer: C

During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Description : During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Last Answer : Answer: B

A circuit is protected from overheating by a/an ___________. A. pyrometer B. thermal overload relay C. magnetic contactor D. overload transformer

Description : A circuit is protected from overheating by a/an ___________. A. pyrometer B. thermal overload relay C. magnetic contactor D. overload transformer

Last Answer : Answer: B

A shading coil used in an AC magnetic controller, functions to _____________. A. reduce vibration and noise in the contactor B. prevent flux buildup in the operating coil C. eliminate arcing when the contacts close D. energize the operating coil and 'pull in' the contacts

Description : A shading coil used in an AC magnetic controller, functions to _____________. A. reduce vibration and noise in the contactor B. prevent flux buildup in the operating coil C. eliminate arcing when the contacts close D. energize the operating coil and 'pull in' the contacts

Last Answer : Answer: A

What is the safety reason to keep the contactor / MCC remote from motor?

Description : What is the safety reason to keep the contactor / MCC remote from motor?  

Last Answer : Contactor = sparking equipment. Not suiting for hazardous location.  

Can we file the pitted contacts of contactor?

Description : Can we file the pitted contacts of contactor?

Last Answer : No, use emery paper and etc.  

What material used for contactor?

Description : What material used for contactor?

Last Answer : Silver-nickel for

Why pure silver is not used in contactor?

Description : Why pure silver is not used in contactor? 

Last Answer : Affected by sulphur, mechanical or arcing damages (adv. Lower voltage drop) 

Why copper contact are not used in contactor?

Description : Why copper contact are not used in contactor? 

Last Answer : Because corrosion rate increases. Poor surface property , large closing force required. 

Why shading rings provided in armature core of ac contactor. Why not for dc contactor?

Description : Why shading rings provided in armature core of ac contactor. Why not for dc contactor? 

Last Answer : Because the force developed is not steady in ac therefore contacts will chatter but if shading ring is used force developed becomes steady due to splitting of phases of flux, therefore contacts becomes bounce free and humming sound reduces.  

Can we use AC contactor in DC circuit?

Description : Can we use AC contactor in DC circuit?  

Last Answer : Yes, but with adequate de-rating.  

DC relay coil or contactor coils must be connected to which side?

Description : DC relay coil or contactor coils must be connected to which side?

Last Answer : Negative side of the DC supply to avoid galvanic effect on the coil, which will corrode the coil.  

What is the difference between relay and contactor?

Description : What is the difference between relay and contactor?

Last Answer : Relay have smaller ratings. Contactor is a high rating relay.

What is the difference between Isolator and Circuit Breaker?

Description : What is the difference between Isolator and Circuit Breaker?

Last Answer : Isolator is an off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. It is manually operated and does ... is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current.

What is difference between fuse and breaker?

Description : What is difference between fuse and breaker?

Last Answer : A: (i) Fuse performs both detection and interruption functions. Circuit breaker performs interruption function only. The detection of fault is made by relay system. (ii) The breaking capacity of ... , replacement is required in the fuse. In case of circuit breaker, replacement is not required.

What is the difference between Isolator and Circuit Breaker?

Description : What is the difference between Isolator and Circuit Breaker?

Last Answer : A: Isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. it is manually operated ... specification 1) rated current 2) short circuit breaking capacity and 3) Instantaneous tripping current.

What is the difference between circuit breaker and isolator?

Description : What is the difference between circuit breaker and isolator?

Last Answer : Isolator is a disconnecting switch which is not having the making and breaking capacity. Bus coupler - 2000A Feeders - 1600 A

Radioactive nuclear waste is treated in (A) Mixer-settler extractor (B) Rotating-disc contactor (C) Pulsed column extractor (D) Bollman extractor

Description : Radioactive nuclear waste is treated in (A) Mixer-settler extractor (B) Rotating-disc contactor (C) Pulsed column extractor (D) Bollman extractor

Last Answer : (C) Pulsed column extractor

The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2 /m3 ) (A) 500 (B) 1200 (C) 900 (D) 800

Description : The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2 /m3 ) (A) 500 (B) 1200 (C) 900 (D) 800

Last Answer : (A) 500

What is a relay? How is it different from a magnetic contactor?

Description : What is a relay? How is it different from a magnetic contactor?

Last Answer : Contactor is a heavy duty switch whereas the relay is light duty switch. Relays can be as simple as 12 V DC solenoids with 12 V, 0.5 A rated contacts. They are used to detect faults on the power system and signal a local or remote switching device (breaker) to trip the circuit.

What is a magnetic contactor? Where is it used?

Description : What is a magnetic contactor? Where is it used?

Last Answer : A contactor is an electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings. Contactors are used to control electric motors, lighting, heating, capacitor banks, and other electrical loads.

State the function of a contactor in a power circuit of locomotive. List different types of it and state one application of each.

Description : State the function of a contactor in a power circuit of locomotive. List different types of it and state one application of each.

Last Answer : Ans: Contactor in power circuit of locomotive is used to connect relevant sections for operation. Connecting or disconnecting the power circuit at different conditions of operation and at different locations. ... heavy power currents. 3) Cam & roller operated - used for group switching.

Which of the following busbar arrangement is generally employed in distribution system: a) One-and-half breaker arrangement b) Main and transfer arrangement c) Ring main distribution system d) Single busbar arrangement system

Description : Which of the following busbar arrangement is generally employed in distribution system: a) One-and-half breaker arrangement b) Main and transfer arrangement c) Ring main distribution system d) Single busbar arrangement system

Last Answer : Ans: C

Coast Guard Regulations (46 CFR) require each switchboard to have ___________. A. non-conductive deck covering at the frount B. non-conductive deck coverings at the rear C. a name plate for each circuit breaker D. all the above

Description : Coast Guard Regulations (46 CFR) require each switchboard to have ___________. A. non-conductive deck covering at the frount B. non-conductive deck coverings at the rear C. a name plate for each circuit breaker D. all the above

Last Answer : Answer: D

Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out? A. De-energize the applicable switchboard bus. B. Bypass the interlocks. C. Secure and tag the supply circuit breaker in the open position. D. Station a man at the circuit supply switch.

Description : Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out? A. De-energize the applicable switchboard bus. B. Bypass the interlocks. C. ... supply circuit breaker in the open position. D. Station a man at the circuit supply switch.

Last Answer : Answer: C

Which of the synchroscope illustrations depicts the appropriate direction of rotation and position for closing the circuit breaker when paralleling AC generators? EL-0053 A. A B. B C. C D. D

Description : Which of the synchroscope illustrations depicts the appropriate direction of rotation and position for closing the circuit breaker when paralleling AC generators? EL-0053 A. A B. B C. C D. D

Last Answer : Answer: D

The schematic diagram shown in the illustration uses symbol 'A' to represent a/an _________. EL-0011 A. non-renewable fuse link B. circuit breaker coil C. overload relay coil D. thermal overload heater

Description : The schematic diagram shown in the illustration uses symbol 'A' to represent a/an _________. EL-0011 A. non-renewable fuse link B. circuit breaker coil C. overload relay coil D. thermal overload heater

Last Answer : Answer: D

An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. cause the slip rings to melt C. cause a low voltage differential to develop between the armature and the bus D. cause high currents to be induced in the field windings

Description : An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. ... between the armature and the bus D. cause high currents to be induced in the field windings

Last Answer : Answer: D

Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed

Description : Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed

Last Answer : Answer: A

Which of the following problems will occur if the circuit breaker of the incoming alternator is closed and it is 180° out of phase with the loaded alternator when paralleling? A. The rotor of the loaded alternator will hunt. B. Severe cross currents will occur which could cause damage. C. The rotor of the incoming alternator will stop. D. Both alternators will parallel 180° out of phase.

Description : Which of the following problems will occur if the circuit breaker of the incoming alternator is closed and it is 180° out of phase with the loaded alternator when paralleling? A. The rotor of the ... The rotor of the incoming alternator will stop. D. Both alternators will parallel 180° out of phase.

Last Answer : Answer: B

Which of the following actions must be carried out prior to closing the alternator circuit breaker according to the graph shown in the illustration? EL-0002 A. Increase the alternator voltage. B. Decrease the line voltage. C. Increase the line voltage. D. Decrease the line frequency.

Description : Which of the following actions must be carried out prior to closing the alternator circuit breaker according to the graph shown in the illustration? EL-0002 A. Increase the alternator voltage. B. Decrease the line voltage. C. Increase the line voltage. D. Decrease the line frequency.

Last Answer : Answer: A

An alternator will fail to produce line voltage as a result of _____________. A. a closed circuit breaker B. oxidized slip rings C. improperly staggered brushes D. exciter generator failure

Description : An alternator will fail to produce line voltage as a result of _____________. A. a closed circuit breaker B. oxidized slip rings C. improperly staggered brushes D. exciter generator failure

Last Answer : Answer: D

In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay

Description : In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay

Last Answer : Answer: B

A circuit breaker for a 300 KW alternator is rated at 470 amperes of full continuous load. The amount of overcurrent allowed is 125%. Which of the following conditions will trip the breaker? A. Sustained current flow of 470 amperes. B. Sustained current flow of 500 amperes for 10 minutes. C. Momentary starting load of 550 amperes. D. Sustained current flow of 590 amperes.

Description : A circuit breaker for a 300 KW alternator is rated at 470 amperes of full continuous load. The amount of overcurrent allowed is 125%. Which of the following conditions will trip the breaker? A. ... 10 minutes. C. Momentary starting load of 550 amperes. D. Sustained current flow of 590 amperes.

Last Answer : Answer: D