The ESDI Model 910210 UV Fail-Safe Switch monitors a UV lamp and reports if the lamp is good or bad. It is used with water purification systems and water vending machines where monitoring the UV lamp sterilization source is essential to prevent the dispensing of non-treated water.
The UV Fail-Safe Switch works by measuring the line current into the UV lamp power supply. When the UV lamp's line current is good, the Fail-Safe Switch is activated. When the line current is bad, the switch is not activated. The switch can be used to control an alarm, or shut down a water vending machine. The circuit requires no additional power to operate, as it steals its power from the lamp's primary line current.