MPCB and Kompaktleistungsschalter are not interchangeable labels for the same motor duty. An MPCB review usually starts with an individual motor branch and its overload, short-circuit and starting behaviour. An MCCB review often starts with a feeder or higher-current distribution boundary, although an MCCB can be used in a motor circuit when its trip unit and coordination are suitable.
Which protection functions belong to the motor branch?
Separate overload protection, short-circuit protection, switching, isolation and control. The motor nameplate current, starting method, acceleration time, cable data and prospective fault current provide the context; frame size alone does not.
When does an MPCB-led review make sense?
An MPCB may suit an individual motor branch when its adjustable overload range, short-circuit performance and starting characteristics match the motor. Check whether the model also supplies the switching or isolation function the drawing requires, rather than assuming that every motor protector has the same scope.
When does an MCCB-led review make sense?
An MCCB is commonly considered for feeders, larger distribution sections or motor circuits that need its frame, trip-unit or accessory options. A thermal-magnetic device may provide overload protection when correctly selected; a magnetic-only device does not provide that function by itself.
Which drawing checks prevent the duties from being merged?
Mark the motor branch, upstream feeder, contactor, overload device, protective-earth path and isolation point. Then check the manufacturer’s tested coordination table for the actual starter combination, voltage and prospective short-circuit current. Do not infer coordination by adding the individual ratings.
What information makes a supplier comparison useful?
Include motor rating and full-load current, starting method, number of starts, supply voltage, fault level, ambient conditions, contactor arrangement, required reset behaviour and the coordination evidence requested. This is more precise than asking for an MPCB or MCCB by nominal frame size.
Which CHAC product routes can be reviewed?
Verwenden Sie die CQV2 motor-protection circuit breaker page for an MPCB starting point and the CQM6 MCCB information for the feeder-side comparison. The selected model still needs to be matched to the approved motor circuit.
Who owns the final protection boundary?
The responsible project electrical designer owns the final boundary, including whether a contactor, overload relay, MPCB or MCCB performs each function. IEC 60947-4-1 und IEC 60947-2 provide standards context, but the exact product and coordination evidence control the project decision.
A clear motor feeder protection schedule should show the boundary between feeder protection, motor-branch protection and control switching, along with the evidence used for coordination.
That separation is particularly important when the same panel contains several motors with different starting methods. One branch’s settings cannot be copied to another without checking nameplate current, starting behaviour and the selected coordination table.
Keep the motor branch coordination note with the approved drawing so a later replacement does not silently change the overload, short-circuit or contactor relationship.
FAQs
Can an MPCB and an MCCB be compared by frame size alone?
No. Compare documented duties against the motor or feeder drawing first.
Does an MCCB automatically protect every motor branch?
No. Motor-branch protection must be confirmed from the design and the selected model.
What motor data belongs in the RFQ?
Include motor rating information, starting method, cable context, and the protection functions assigned on the drawing.
How does this differ from contactor coordination guidance?
Coordination with a contactor is a related but separate review once the protective-device duty is defined.
What evidence should suppliers return?
Return proposed model identification and the documents that support the requested protection duties only.
Who owns the final protection boundary?
The responsible project electrical designer owns the boundary using the approved drawings and selected-model data.
