A new temperature-monitoring relay introduced by industrial automation specialist Omron provides inexpensive yet highly effective protection against over-temperatures. The new K8AB-TH is designed specifically for monitoring abnormal temperatures and preventing excessive and possibly damaging temperature rises in installations such as furnaces and ovens.

Manufacturers of high-temperature systems such as furnaces have traditionally relied either upon thermistors or trip amplifiers for over-temperature protection of their equipment. Thermistors have the advantage of being inexpensive, but the over-temperature protection they provide is relatively rudimentary and not all of them include appropriate means for resetting. Trip amplifiers provide highly sophisticated temperature monitoring and protection but are often regarded as prohibitively expensive.

The new K8AB-TH temperature-monitoring relay from Omron falls between these extremes by offering simple and intelligent features for temperature alarm and simple ON/OFF control, yet at a price significantly less than that of high-end units like trip amplifiers.

With functions set by a simple DIP switch, and the alarm threshold set directly by rotary switches on the front, the K8AB-TH is also easy to configure.

The units come in a slim space-saving housing with a width of just 22.5 mm suitable for DIN-rail or direct panel mounting. They feature multiple inputs with support for both thermocouples and Pt100 sensors. For the alarm output, a 3 ampere changeover relay is provided. In contrast to many other, comparable monitoring relays, the K8AB-TH incorporates an output latch function with front-button latch reset, SV protection and a selectable relay fail-safe mode that provides self protection against power or unit failure. Two LEDs, one for power and SV protection and one for alarm and unit condition, provide clear status indication.

Omron's new temperature-monitoring relay provides inexpensive over-temperature protection.

The new series currently comprises four application-specific models covering high (0 to 1800 oC) and low (0 to 399 oC) temperature ranges and high (100 to 240 V) and low (24 V) supply voltages.