« Motor Protectors

Self-hold 7AM Series (SH7AM)

Self-hold 7AM Series Thermtrol’s innovative Self-Hold 7AM thermal protector combines the protection of a Klixon® 7AM with a self-holding feature. Designed to prevent overheating in mo- tors, the Self-Hold 7AM offers the best attributes of one shot protectors and auto reset protectors in a single package. The Self-Hold 7AM, once activated in a fault condition, maintains its open state until power is removed. No reset button here-simply remove power and the device will cool and reset. This inherent design feature adds an extra level of security over automatic reset devices of any type. It is the reliable, cost effective solution for numerous applications.

Details & Specifications

Type A, Radial Lead Configurations

Type B, Axial Lead Configuration

Here's How it Functions

Developed by Thermtrol, the Self-Hold 7AM is a Thermal Protector/PTC Heater combination. The PTC Heater is electrically located across the contacts of the protector.

When the protector contacts are open, the heater is in series with the load. The heater then maintains the temperature sensitive bimetal of the protector in an open state.

To reset the Self-Hold 7AM, power must be removed for sufficient time to allow the Self-Hold 7AM to cool to below the protector’s reset point.

Bi-metal Options

Self-Hold 7AM performance is dependent upon the applied current as well as temperature. Differenct Bi-metals are incorporated to achieve various performance characteristics. In applications where temperature rise is less than 2°C per second, use low-resistance ratings. High-resistance Bi-Metal is recommended for applications with 2°- 5°C per second rates of temperature rise. Contact Thermtrol for additional application consideration if the rate of temperature rise exceeds 5°C per second. Use these curves to determine which Bi-Metal may trip in the manner required for your application.


Thermtrol’s state-of-the-art automated lead processing equipment can produce lead wires to meet customer application needs for overall length, wire type, wire size, terminated connection and stripped length requirements. Standard lead size is 18AWG. 20AWG-14AWG is also available.


In order to achieve optimum heat transfer from the protected medium or ambient to the thermostat, the Self Hold 7AM has been designed with the case connected to the bimetallic disc. This feature makes it necessary to electrically insulate the 7AM from the mounting surface. Typically, this is accomplished with a Mylar sleeve marked with the part number. Custom markings and other sleeve materials are available.

Agency Approvals

Numbering Systems