What are 52a and 52b contacts?

What are 52a and 52b contacts?

The 52a contact follows the status of the breaker. A form ‘b’ contact represents a Normally Closed (N.C.) contact. When the breaker is open, the 52b contacts are closed. When the breaker is closed, the 52b contacts are open.

What is 52a and 52b?

52a – AC circuit breaker position (contact open when circuit breaker open) 52b – AC circuit breaker position (contact closed when circuit breaker open)

What is 52a contact?

52a is a heavy-duty contact that is rated to interrupt that current so that the tripping devices (relays) do not have to. 3. Trip coil is not rated for continuous current. It needs to be de-energized as soon as possible after it has done its job to trip the breaker.

Which contacts of circuit breaker opens?

When the circuit breaker opens, the main contacts part first and then the arcing contacts part, “drawing out” the arc across the air gap.

What is MOC and TOC?

One of these is the question of mechanism-operated cell (MOC) and truck-operated cell (TOC) switches, where there still is uncertainty as to what they are and why they exist. 52a – a circuit breaker operating mechanism actuated switch that is closed when the main contacts are closed.

What is the function of closing coil in ACB?

The closing coil is an electrical accessory used for controlling the closing of the power contacts of the circuit breaker. The springs of the circuit breaker are to be loaded before the action of the closing coils. It is controlled by NO contact.

What is the difference between tripping and closing coil?

Therefore, operating the closing latch requires greater force than for operating the tripping latch i.e. stronger magnetic field is required for closing than for tripping. Hence, closing coil resistance is designed much less than tripping coil resistance to have a stronger magnetic field.

What are circuit breaker contacts made of?

The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting (opening) the circuit. Contacts are made of copper or copper alloys, silver alloys and other highly conductive materials.

What is contact circuit breaker?

The purpose of the contact breaker is to interrupt the current flowing in the primary winding of the ignition coil. This causes a very high voltage to appear at the coil output for a short period—enough to arc across the electrodes of a spark plug.

What are MOC and TOC contacts?

What is a TOC switch?

4.3.2 Truck-Operated Contact Auxiliary Switches (TOC switch) TOC auxiliary switches are mounted in the circuit breaker compartment and operate when the circuit breaker is moved to the operating position. TOC switches may be used for interlocking and remote position indication.

What is shunt trip?

A shunt trip device is an optional accessory in a circuit breaker that mechanically trips the breaker when power is applied to the shunt trip terminals. The power for the shunt trip does not come from within the breaker, so it must be supplied from an external source.

What is 52A on a circuit breaker?

A form ‘a‘ contact represents a Normally Open (N.O.) contact. Thus when the breaker is open, its 52a contacts are open. When the breaker is closed, the 52a contacts are closed. The 52a contact follows the status of the breaker.

When the breaker is closed the 52B contacts are open?

When the breaker is closed, the 52b contacts are open. With the 52a contact in the trip circuit (as shown in the scheme above), once the breaker opens, this contact opens too. Now no matter what the relays do, the trip coil is isolated.

What is the difference between 52A and 52b contacts?

When the breaker is closed, the 52a contacts are closed. The 52a contact follows the status of the breaker. A form ‘ b ‘ contact represents a Normally Closed (N.C.) contact. It operates exactly opposite of what an ‘a’ does. When the breaker is open, the 52b contacts are closed. When the breaker is closed, the 52b contacts are open.

What is the use of 52B contact in relays?

Protection functions: 52b contact is used as an input, which indicates breaker status (position) to the relay logic. The REL301/2 relays use the 52b contacts in the following protection logic functions: 1. Loss of Potential Logic (LOP) The LOP function is turned off if the breaker is open.