Eaton HMCP003A0C Series C motor circuit protector

A motor circuit protector like the Eaton HMCP003A0C is a magnetic-only device. It provides short circuit protection for a motor branch circuit and is applied together with a separate overload relay in the starter, which handles the running overload. A standard thermal-magnetic molded case breaker combines both functions in one device. If you are building a combination motor starter where the contactor and overload relay already cover overload, the HMCP is the protector that belongs in it; if there is no overload relay in the circuit, an MCP is not a substitute for one.

The catalog number is HMCP003A0C and it is an Eaton Series C motor circuit protector. Distributors matching a bill of material should order on that full string, including the trailing C, since the HMCP family uses the numeric block for the frame ampere rating and the suffix characters for the trip adjustment and construction.

Plan on 8 x 5 x 5 inches for the Series C motor circuit protector. That is the figure to use when you are laying out a starter enclosure or checking that the protector plus the contactor and overload block will sit inside the backpan you already have.

Eaton publishes a dedicated spec sheet for the HMCP003A0C, and it is the document to pull for the adjustable instantaneous trip settings and the interrupting ratings when used in a combination starter. Engineers specifying the device for a submittal should attach that sheet rather than rely on a generic HMCP data page, because trip values differ across the frame sizes in the family.

It weighs 4.5 lb. Light enough for a one-hand mount on a DIN or backpan layout, but worth knowing if you are loading out a panel build and totaling weight on a shipment of several devices.