Motor Circuit Controllers

KT7 Control & Protection to 45A




CL7_KTA7and CA7


UL Approved for a Wide Variety of Applications

Sprecher + Schuh's KT7 series of Motor Circuit Controllers are some of the most versatile and technologically advanced control products available today. These devices can be used in a variety of control schemes that reduce panel space, simplify installation and eliminate the need for more expensive equipment.


  • Current-limiting short circuit protection
  • Class 10 thermal overload protection
  • Switching
  • Signaling

Variety of models... Increased ratings...

Sprecher + Schuh's KT7 controller family offers higher interrupting capacities (KAIC ratings), improved Type 2 Coordination and a midsize frame rated to 45A. In addition, the line includes "high break" 25A and 32A devices which offer greater withstand ratings in a smaller frame size.

Designed for multiple applications

UL rules allow KT7 Motor Circuit Controllers to be used in a wide variety of applications, including:

  • Manual Starter Applications
  • Traditional Group Motor Applications with compliance to the new Tap Conductor Ratings
  • Motor Disconnect Applications
  • Self-Protected Manual Combination Starter Applications (Type E)
  • Individual Combination Starter Applications
  • Multi-motor Starter Combination Applications

Construction Type E Listing

Improved current limiting and breaking capacity has allowed KT7s to be UL / CSA listed as self-protected (Construction Type E) manual combination motor controllers. This eliminates the need for an upstream fuse or circuit breaker when using the KT7 as a manual motor starter. In addition, KT7s also meet UL requirements for "at-motor disconnects," which means they can be used in an enclosure with a lockable handle as a manual motor starter for individual circuits, and are also an approved means of motor disconnect. 

Type E + combo starter + economy = "Ecombo" starter

When the KT7 self-protected manual combination starter is combined with Sprecher + Schuh's CA7 contactor to provide remote operation, we now have an alternative to the classic combination starter. We call these "Ecombo" starters, which save significant dollars and panel space over conventional combo starters. Ecombo starters are available for applications up to 30HP (@460/600V).

Multi-motor applications... Popular and money saving

Because of KT7's Construction Type E-UL Rating as a self-protected combination starter, many group motor installations can utilize an even simpler design and less expensive equipment. The result is minimum panel size and maximum flexibility while avoiding cumbersome NEC group motor rules. 60mm Bus Bar systems can be utilized to provide a cost effective and flexible multi-starter panel assembly.

Excellent short circuit protection characteristics

In the event of a short circuit, the contacts are opened by magnetic, non-adjusting tripping elements in times approaching 3/1000 of a second. This results in the extremely rapid buildup of an arc voltage which limits the current of the short circuit to a very low level. Because of this superb current limiting capability, KTA Motor Circuit Controllers have a short circuit capacity of up to 65kA at 480V and up to 47kA at 600V.

Superb thermal overload protection

Every KT7 device is individually calibrated at the factory for the smallest and largest current it can handle. When coupled with automatic ambient temperature compensation over a range of -25°C to +60°C, very accurate thermal overload protection is obtained. In addition, the KT7 is a Class 10 device. It trips within 10 seconds under locked rotor conditions (6 x FLA). This better protects today's T-Frame motors.

Special units for special applications

KTC7 controllers are available with a fixed magnetic trip set at 16...20x the maximum value of the current adjustment range (as opposed to 13x for the KTA and KTB7). This prevents nuisance tripping in applications utilizing high efficiency motors for example. The KTB7 model is available without the thermal trip feature if a separate motor overload is required. Combine KTB7 with a CA7 Contactor and CEP7 Overload Relay to create the CLT7 3-component Ecombo starter.

Other protection features

All KT7 Motor Circuit Controllers provide accelerated tripping under single phase conditions. This is accomplished with a special "differential tripping" mechanism built into each device.


Available in: AL, N.W. FL and MS