On May 29, 2026 in Industrial, Industrial Automation, Motor Control, Power by Schneider Electric

Single-motor-starter plug-in solutions streamline control panel construction and improve performance

Electric motors are responsible for a large share of industrial energy use. They power pumps, conveyors, compressors, processing equipment, and nearly everything in between. The motor starter is an important part of these systems because it controls and protects the motor during operation.

Pressing the “start” button results in a distinctive clack, and the equipment comes to life as the motor quickly ramps up to full speed. That clack is the sound of an electromagnetic switch closing inside a combination motor starter, designed to handle the inrush of current to a stationary motor effectively and safely. This operation is repeated hundreds of millions of times each day in industrial environments, where electric motors account for roughly 70 percent of total electricity consumption.[1]

Given the critical role that motors and motor starters play in all industries, their operational characteristics are subject to standards under the umbrella of industrial control panels, switch gear, and control gear; governed by Underwriters Laboratories (UL) 508A[2] and International Electrotechnical Commission (IEC) 60947.[3] Both of these standards cover equipment working at 1,000 volts AC or less, calling out requirements for combination motor starters themselves and explaining how they function in a larger context. These standards call for motor starters to comply with regulations on a number of elements, including conductor placement, terminal spacing, and how the panel builder arranges and wires the devices inside the control panel housing.

This blog details how modular combination motor starters are key to building simpler, more reliable motor branch circuits in today’s industrial control panels, revealing how configuring a single starter family to meet diverse motor requirements can streamline panel design and support UL 508A and IEC 60947 compliance across modern manufacturing facilities.

Feeder vs. Branch Circuits in Motor Control Design

A motor starter is usually attached to a branch circuit rather than a feeder circuit. The difference between these circuit types relates to placement of overcurrent protective devices. A feeder circuit generally distributes power to multiple branch circuits with no intermediate overcurrent protective devices. Motor starters connected directly to feeder lines must have capacity based on the total load the feeder handles, including all the motors it supports, plus a significant overage allowance for safety. These arrangements are rare because of how complex this approach is.

Since the only element necessary to create a branch circuit is a branch circuit protective device, it is far simpler to use this approach, even in situations where multiple motors are supported by one branch. This practice has its own rules described in National Electrical Code® (NEC) sections 430-112 and 430-53.[4]

Motor Starter Functions

A combination motor starter must provide four functions, in a specific order, from supply to motor. First, a manual power disconnect, such as a switch or breaker, isolates the motor from the main power supply. This is followed by short circuit motor disconnect protection, which typically uses fuses or breakers, to interrupt power instantly in response to a high-current fault. Under the proper conditions, such as with a Type E motor starter, this can serve as the branch circuit protective device, allowing the starter to be connected directly to the feeder supply while treated as a branch circuit. Next is the motor controller, which consists of the contacts to turn power on or off. These can be a full-load switch or soft-starting function to manage voltage, as well as limit inrush current and mechanical stresses. Finally, there is motor overload protection, which uses thermal or electronic relays to interrupt power when the motor draws excess current on a sustained basis.

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