Electrical Contactors vs. Circuit Breakers

It's like the difference between using the brakes on your bicycle and sticking a broomstick in the spokes. Both stop the bike, but only one was meant to be done regularly.

Both can make and Break a circuit.However the similarity ends there.A contactor is suitable for a no of operations in its life time.It cannot however open out when there is a fault current .Hence contactors normally backed up by Fuses.Breaker can close and open on fault current.However its not suitable for a large no of operations.as compared to contactor.A comaprisson can be made by studying the catalog of manufacturers as regards max no of operations in its life time.As I remember a contactor can be 8-10Million as compared to a breakers 10-15000.

Similarity : Both are used for making & Breaking the circuits

Difference : (1) Contactor can only be used upto cirtain current level while breaker can break even the fault current in kilo amperes (2) Contactor is part of the circuit while breaker are used at start point of circuit (3) Breaker having settings to trip on pre-set current while contactor do not have any tripping arrangement.(4) conctor are only Air Break type while Breakers are of differet types e.g. oil CB,Vaccume CB, SF6 CB, Air CB, Forced air CB... according to the type of the arc exinguishing media is used for.

A contactor is used simply to make or break contacts. It can not be used for any other purpose.

While a circuit breaker does much more. It opens and closes a circuit by non- automatic means. It can also be set to trip at various values of current, time or both within a predetermined range. It does the above and other tripping funtions without damage to itself when properly applied within its rating.

For any other questions/ clarifications, let me know.

Mr Thakral

Simplified...

A contactor has a small air gap between the contacts. If used to open a circuit with a high current fault, an arc can easily form. Both the contactor and the wiring would be severely damaged by the arc and the high fault current.

A circuit breaker is designed to quickly open a faulted circuit by separating the contacts a much larger distance AND usually uses one or more methods to quickly disperse and quench any arc that might form.

Contactor: Basically used for open/close the circuit with n/o and n/c contacts and are used for automatic operation equiped with a relay and timer, and its a part of a circuit and protect the load set on limited current at certain level, and also suitable for multi-operations of various loads.It simply belongs to a control device family.

Circuit Breaker (instantenous type) open the entire circuit immediately during fault currents and simply can reset manually.

Contactors have a very limited making & breaking capacities. For example, if your application is a conventional squirrel cage AC Induction motor, then a contactor can make only 10 times its rated current safely and can break only 8 times its rated current safely. Beyond these limits, there is bound to be damage to the contactor, to the installation and even to the opertaing personnel. Yes! There can be an explosion too!

Whereas, circuit breakers do have a very high making & breaking capacities. Breaking capacities of 75 kilo-amperes & making capacities of 165 kilo-amperes are quite common ion today's circuit breakers.

Hi,

Contactors are being used for making and breaking the circuit on the basis of required logic by using relays.

Examples

1.Contacts used in power factor correction to switch ON and OFF the Capacitor bank as per the APFCR logic to maintain the desired level of PF.

2.Contactors used in Zonal lighting controls as per the PLC logic and timer.

3.Contactors used in DG Neutral switching as per the PLC logic

Circuit Breakers are mainly used for, Making and Breaking the circuit with enough short circuit rating level for safe operation, CB can be used independently without any logical support and can be used with logics also. MCB, MCCB, ACB, VCB are circuit breakers with KA ratings