Modular Combination Motor Starters Simplify Industrial Branch Circuits
Single-motor-starter plug-in solutions streamline control panel construction and improve performance
(Source: Olga/stock.adobe.com)
Published May 29, 2026
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.
With a combination motor starter, all four of these are included in the starter housing to minimize wiring inside a control panel. (Figure 1)
Figure 1: Diagram illustrating the four essential functions of a combination motor starter: disconnect the power supply, provide short-circuit protection, control motor operation, and protect the motor from overload conditions. (Source: Schneider Electric)
Starter Types
In the US, UL 508A lists six motor starter types, A through F, roughly in order of introduction. They differ primarily in the types of protection devices used and how the different stages are separated (Figure 2).[5]
Figure 2: Comparison of UL 508A motor starter types A through F. (Source: Mouser Electronics/Author)
Because Type E combination motor starters integrate multiple required functions into a single package, they are commonly selected for applications where panel space is limited, wiring complexity must be reduced, and compliance with applicable standards needs to be simplified.
Modular Combination Starters for Efficient Panel Design
For industrial environments that demand high-endurance on-off motor control, Schneider Electric offers two families under the TeSys banner. TeSys Ultra is an all-in-one, Type E, advanced combination motor starter for applications up to 32A. Another option for efficient panel design that ranges up to 65A would be a Type F two-component solution. Schneider Electric offers the TeSys Deca family, where when using a specified combination of GV Manual Motor Starter and LC1D contactor your motor circuit can achieve up to 65kA SCCR with no additional components or protection.
The TeSys Ultra Combination Motor Starters assemble all protection, switching, and disconnect functions in a single package, designed to save space inside panels. Integrated control unit modules (Figure 3) snap into a power base, providing options that include:
- Reverser
- Current limiter
- Line phase barrier
- Soft starter
- Multifunction control unit
- Internal diagnostic capabilities via multiple communication protocols
By consolidating these functions, TeSys Ultra reduces the number of devices that must be checked or reset after a trip. Once the fault condition is resolved, the starter can be reset quickly and safely—either through remote or automatic reset options, or via a fast manual reset, depending on the model. This enables motors to return to operation with minimal delay, which is a key advantage in applications where uptime is critical.
Figure 3: Schneider TeSys Ultra combination motor starters use modular concepts with interchangeable elements to support basic and more complex functionality. (Source: Schneider Electric)
When problems do occur in the field, loss of a single motor on a production line or a critical pump can bring production to a halt. A TeSys Ultra starter can be equipped with function modules to provide diagnostic data to assist troubleshooting. For example, it can differentiate between a trip caused by an overload or a short circuit, warn when the motor is pulling more than its normal full-load current, or alert when the current of the three phases is out of balance. Aside from these motor malfunctions, if a problem is in the starter itself, individual components can be pulled out and replaced in minutes—often without any rewiring—to get production running again. This interchangeability helps with parts inventory since a few spares can service a large installation within a facility.
Supporting Simplified Panel Construction and Reliable Operation
Control panel designers and the companies operating them value simplicity and reliability. Rather than create panels using large numbers of discrete components that must be assembled and wired manually, there are more streamlined approaches using modular assemblies, such as TeSys Ultra combination motor starters. The ability to use plug-in components simplifies and accelerates assembly, troubleshooting, maintenance, and modification. When a production line is down, time wasted having to trace circuits can be costly. When modules are individually listed, their combinations are also listed, which makes certification more straightforward, and in turn, operation for the long term becomes more manageable.
[1]https://www.iea-4e.org/emsa/publications/policy-brief-electric-motor-systems-why-are-they-important/
[2]https://www.ul.com/resources/ul-508a-third-edition-summary-requirements
[3]https://www.ul.com/resources/industrial-control-equipment-transition-iec-standards
[4]https://www.nfpa.org/education-and-research/electrical/understanding-nfpa-70-national-electrical-code; https://www.nfpa.org/codes-and-standards/nfpa-70-standard-development/70
[5]https://www.ul.com/resources/short-circuit-current-ratings-combination-motor-controller-components
Author Bio
Peter Welander, now semiretired, has been working as a freelance writer and editor for more than 10 years, following seven years as a senior editor and content manager for Control Engineering magazine. During this time he has written heavily about industrial automation, primarily in process industries. Responsibilities have also included audio and video production, podcasts, and blogging.
Moving into the publishing world followed many years working in sales and marketing management, engineering, and operations for a variety of industrial manufacturers. One capability that he has had throughout his career is the ability to grasp technical concepts and explain complex ideas clearly. His personal interests include photography, a machine shop, woodworking, and pipe organ building.