This circuit details a system that resets to an off or safe condition when power is cycled. The circuit also assures the system is in a known state at power up.
This example uses a single VIVISUN High Capacity Body that contains a single switch pole, a NEXSYS Electronic Latch (EL1) and an open position.
In this application, when the HOT LIQUID switch is depressed the (H1) switch contact provides ground to the /TGL input (J2) of the EL1 causing the Q output (K2) to transition from open to ground illuminating the “ON” legend and drives an external relay for the water heater. Pressing the switch again will turn the system off. When 28VDC power pin (J4) is cycled the EL1 resets transitioning the Q output to open (high impedance) turning the “ON” legend off and cancels the hot water relay.
This is a basic application that highlights the Power-On-Reset feature of the EL1. This feature may be used in many different applications and is an effective method of assuring complex systems, are in a known power up state. The EL1 has an effective tolerance to power interruption to 50ms and for assured reset, power should be interrupted for 5 seconds minimum.