Remote Control of Caltherm Thermal Actuators

Caltherm Thermal Actuators can be controlled to actuate independently of the medium into which they are immersed. This is accomplished by attaching a heat source to the thermal element itself. The heat source can be activated by applying an appropriate voltage, causing the expansion material to melt and expand. Thus, forcing the piston to extend. When the heat source is deactivated the expansion material will cool and assume its cold state volume, returning the piston to its start position, under the influence of the return spring. This construction results in a two position actuator controlled by the simple application and removal of an applied voltage, similar to an electric solenoid. Caltherm Thermal Actuators therefore, can   be used to replace simple solenoid functions, especially where high piston forces are required, eliminating the need for high power requirements and large size envelopes to accommodate the bulky solenoid.

The heat source is made an integral part of the Caltherm Thermal Actuator by encapsulating a PTC (Positive Thermal Control Thermistor) to the bronze cup containing the expansion material. Because the electrical resistance of the PTC increases with its rise in temperature, the proper selection of the PTC and expansion material must be made to prevent overheating and over-stroking of the element.

Caltherm Thermal Actuators are available with heat sources (PTC"s 12 volt, 24 volt, 110 volt, and 220 volt). Other models can also be supplied with a wide variety of stroke force and response time.