HG102A5 by Danaher

The HG102A5 is a repeat-cycle timing relay produced by Danaher within the Timers and Controllers series. It uses an internal synchronous motor and cam assembly to generate alternating on and off periods for solenoids, heaters, or sequencing interlocks in automated equipment. By cycling loads at a fixed line frequency, it provides predictable dwell or overlap windows that can be coordinated with PLC logic or mechanical processes. The plug-in octal base simplifies panel installation and allows the relay to be removed without disturbing permanent field wiring.

During operation, the relay draws 2.5 VA at 120 VAC, allowing it to share a control transformer with other low-power devices such as indicator lights. Its two outputs are furnished as two SPDT contacts, providing separate switching paths for control circuits. Each pole can switch up to 10 A at 120 VAC with a resistive load. Timing is governed by the synchronous unidirectional motor, which provides a full cycle of 150 seconds. A minimum setting of 2 seconds and a maximum dwell or overlap of 2 seconds permit short, controlled pulses. The dial is graduated in seconds, and the circuit repeats with an accuracy of ±0.5% of the dial setting, helping successive cycles remain synchronized. The selected timing mode is an on/off repeat cycle, and the dwell or overlap period is adjusted mechanically through the cam stack. The switch contacts are rated for 250,000 operations when switching a 10 A load, supporting extended use in repetitive industrial processes.

The mechanical components are rated for 10,000,000 operations, allowing the camshaft and gearing to withstand prolonged service without frequent recalibration. The contacts operate across a temperature range of -20 to 140 °F, making the relay suitable for cold rooms and heated control panels. Line power is supplied at 120 V and 50 Hz, which supports stable operation on compatible control circuits. The synchronous motor links its timing motion directly to the incoming frequency, while the adjustable cam arrangement controls the relationship between energized and de-energized intervals. This design supports recurring machine sequences that require consistent timing without electronic programming.