MCB types based on Number of poles

Posted on Posted in Electrical, Study Material

Types of MCBs used (Poles)

SP – Single Pole In Single Pole MCB, switching & protection is affected in only one phase.
Application: Single Phase Supply to break the Phase only.
SPN – Single Pole and Neutral In Two Pole MCB, switching & protection is affected in phases and the neutral.
Application: Single Phase Supply to break the Phase and Neutral.
DP – Double pole In Two Pole MCB, switching & protection is affected in phases and the neutral.
Application: Single Phase Supply to break the Phase and Neutral.
TP – Triple Pole In Three Pole MCB, switching & protection is affected in only three phases and the neutral is not part of the MCB.
Application: Three Phase Supply only (Without Neutral).
TPN – Triple Pole and Neutral In TPN MCB, Neutral is part of the MCB as a separate pole but without any protection given in the neutral.
Application: Three Phase Supply with Neutral
4P – Four Pole 4pole MCB for 4 wires connections, the one additional 4th pole for neutral wire connection so that between neutral.
Application: Three Phase Supply with Neutral with protection

Note : We should use TPN MCB for a three phase supply if there are more than one incomers i.e. one utility supply and one DG back up supply. If there is a heavy unbalanced load connected to the system, we should use 4P MCBs.

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