Dwyer Instruments: Series 3868, Tell Tale Jr. Open Heater Detector
Indicates Open Loads
The Tell Tale Jr.™ Open Heater Detector is designed to indicate an open heater or other resistive load. Several models are available for various applications. The LED models light an LED when current is flowing in the circuit. If current stops flowing, the LED turns off. Solid state switch models provide either a logic output for DC applications or a triac output for AC applications. These models will satisfy those applications that need to send heater data to a PLC or computer having an appropriate power supply. They are provided with 4 foot leads. If the triac output model is used to drive an inductive load (relay coil, etc.) then the 3138-0412 snubber network is required. While the Tell Tale Jr.™ Detector is self-powered there is no power loss in the monitored load circuit when installed.
The Tell Tale Jr.™ Detector installs easily in new or existing systems. It consists of a specially designed doughnut shaped current transformer that is installed by passing one of the heater hookup wires through its center one or more times. Nylon tie wraps are included to anchor the detector to the wire. The detector can be installed on loads with ratings of 1 to 100 amperes. LED models on a 4 foot extension cable include a mounting bezel to facilitate mounting the LED on the front of a panel board. Cables may be extended up to 3,000 feet if necessary using 22 ga. copper wire.
Ambient temperature range for LED models is 0 to 70°C, logic output 0 to 60°C and triac output 0 to 40°C at 0.5A with de-rating to 0.35A at 60°C.