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Switchboards Medium Voltage

Circuit breakers are protective devices, which perform two primary functions:

Open and close electrical circuits

Similar to switch, circuit breakers are the primary way to energize and de-energize the circuit. Specialized circuit breakers can also be opened or closed remotely.

Switchboard Mechanical Parts

Breaker Pan Assembly
Grounding contact	Grounding contact grounds the breaker in positions.
levering system	The levering system prevents removal of the breaker in any position other than the Disconnect (or Test) position.
control wiring	The control wiring is arranged for pullout disconnecting by means of a 25-point female receptacle arranged to connect to a male plug on the breaker. The secondary disconnect is the connection for the control leads between the removable breaker and the stationary housing (see the breaker instruction book for further description).

Secondary
Manual Secondary	Represents a manually engaged secondary assembly that requires the customer to engage the secondary harness manually when the breaker is in the Disconnect position. When engaged, the breaker will now be in the Test position.
Auto Secondary	Indicates an automatically engaged secondary as offered on the BPI pan assembly and requires no manual input from the customer to engage the secondary harness. The secondary harness will engage automatically when the breaker is levered-in to the discrete Test position. The secondary harness will then disengage automatically when the breaker returns to the Disconnect position.
Racking screw	Racking screw performs breaker insertion and withdrawal.
Moving blocks	Moving block couples to breaker for insertion and withdrawal.
Slider	Slider is used with #8 to prevent levering a closed breaker. May also be used in conjunction with #12 to padlock a breaker in either position.
Position Indicator	Indicates when the breaker is in the fully connected position.

The breaker MOC (mechanism-operated compartment) switch is an assembly of switches that is operated by a lever on the breaker mechanism. It can contain as many as 15 normally closed and 15 normally open contacts (beneath the cover) in the standard design. The MOC switch is activated by the breaker closing. It extends a plunger out the bottom of the mechanism and Pushes down on the MOC switch operating mechanism. This, in turn, transmits the motion to operate the switch.

The TOC switch (truck operated compartment) has nine poles in the normal design – four contacts make and five break as the breaker is levered to the connected position. As the breaker is being levered into the connected position, a bracket on the breaker pushes the TOC switch lever during the last inch of travel. As a result, the TOC switch can be used to electrically indicate whether or not the breaker is in the connected position (beneath cover).

The breaker MOC (mechanism-operated compartment) switch is an assembly of switches that is operated by a lever on the breaker mechanism. It can contain as many as 15 normally closed and 15 normally open contacts (beneath the cover) in the standard design. The MOC switch is activated by the breaker closing. It extends a plunger out the bottom of the mechanism and Pushes down on the MOC switch operating mechanism. This, in turn, transmits the motion to operate the switch.

The TOC switch (truck operated compartment) has nine poles in the normal design – four contacts make and five break as the breaker is levered to the connected position. As the breaker is being levered into the connected position, a bracket on the breaker pushes the TOC switch lever during the last inch of travel. As a result, the TOC switch can be used to electrically indicate whether or not the breaker is in the connected position (beneath cover).

Switchboard Electrical Wiring

Breaker Pan Assembly
Grounding contact	Grounding contact grounds the breaker in positions.
levering system	The levering system prevents removal of the breaker in any position other than the Disconnect (or Test) position.
control wiring	The control wiring is arranged for pullout disconnecting by means of a 25-point female receptacle arranged to connect to a male plug on the breaker. The secondary disconnect is the connection for the control leads between the removable breaker and the stationary housing (see the breaker instruction book for further description).

Secondary
Manual Secondary	Represents a manually engaged secondary assembly that requires the customer to engage the secondary harness manually when the breaker is in the Disconnect position. When engaged, the breaker will now be in the Test position.
Auto Secondary	Indicates an automatically engaged secondary as offered on the BPI pan assembly and requires no manual input from the customer to engage the secondary harness. The secondary harness will engage automatically when the breaker is levered-in to the discrete Test position. The secondary harness will then disengage automatically when the breaker returns to the Disconnect position.
Racking screw	Racking screw performs breaker insertion and withdrawal.
Moving blocks	Moving block couples to breaker for insertion and withdrawal.
Slider	Slider is used with #8 to prevent levering a closed breaker. May also be used in conjunction with #12 to padlock a breaker in either position.
Position Indicator	Indicates when the breaker is in the fully connected position.

The breaker MOC (mechanism-operated compartment) switch is an assembly of switches that is operated by a lever on the breaker mechanism. It can contain as many as 15 normally closed and 15 normally open contacts (beneath the cover) in the standard design. The MOC switch is activated by the breaker closing. It extends a plunger out the bottom of the mechanism and Pushes down on the MOC switch operating mechanism. This, in turn, transmits the motion to operate the switch.

The TOC switch (truck operated compartment) has nine poles in the normal design – four contacts make and five break as the breaker is levered to the connected position. As the breaker is being levered into the connected position, a bracket on the breaker pushes the TOC switch lever during the last inch of travel. As a result, the TOC switch can be used to electrically indicate whether or not the breaker is in the connected position (beneath cover).

The breaker MOC (mechanism-operated compartment) switch is an assembly of switches that is operated by a lever on the breaker mechanism. It can contain as many as 15 normally closed and 15 normally open contacts (beneath the cover) in the standard design. The MOC switch is activated by the breaker closing. It extends a plunger out the bottom of the mechanism and Pushes down on the MOC switch operating mechanism. This, in turn, transmits the motion to operate the switch.

The TOC switch (truck operated compartment) has nine poles in the normal design – four contacts make and five break as the breaker is levered to the connected position. As the breaker is being levered into the connected position, a bracket on the breaker pushes the TOC switch lever during the last inch of travel. As a result, the TOC switch can be used to electrically indicate whether or not the breaker is in the connected position (beneath cover).