Stafford Instruments Ltd | manufacturer of temperature controllers | pyrometers | thermocouples

Stafford Instruments manufacture a range of different Temperature Controllers. Broadly speaking our controllers can operate in ONE OR BOTH of two modes explained below:


Signal Mode: (ST31XA/ST32X and ST501A)
In Signal Mode the controller provides a signal(s) to remote relay(s) or contactor(s) which is (are) normally located inside the kiln casing. The Heavy Duty Relay or contactor switches the High Power to the Kiln Elements and not the relays mounted internally in the controller itself. Controllers operating a kiln in this mode are usually connected to the kiln via a controller cable. This cable is normally a composite cable consisting of 10 cores. 2 of these cores are temperature compensated cores specifically for the thermocouple wiring. This specialised cable is not readily available. Stafford Instruments have it specially manufactured by one of the leading cable manufacturers in the United Kingdom. Most modern kilns have a socket mounted on the kiln. This socket mates to an opposite gender plug which is fitted to the end of the controllers umbilical cable. The Standard type of Plug and socket used by the majority of Kiln Manufacturers is a Harting 7D 8Pin Square Type. A Minority of Kiln Manufacturers use a CPC14 Pin Round Plug and socket. With the development of multi-zone controllers such as the ST325 and ST326 an upgraded type of plug and socket have to be used to cater for the additional wiring required. For multi-zone controllers the Harting 15DX plug and sockets are used. Images of the different types are shown below:

Power Mode: (ST221 / ST222 and ST31XPA)
In Power Mode the relays inside the controller switch the actual power to the kiln elements directly. In this mode a heavy duty cable is used between the controller and the kiln, and the above type of connectors and cable are NOT used. The ST221 and ST222 are Power controllers and can switch a Max Load of 3KW or 13A directly. The ST31X Range of controllers when configured in Power Mode ( selectable by an internal link) can switch a maximum of 5KW or 20A. Below is a table that shows the mode type that our differing controller types can operate in.