Automatic transfer switches (ATS) are part of a backup power system. They provide a smooth changeover to generator power when a mains power outage occurs.
A local generator supply company contacted us wanting to use our SMS Lite as a notification and remote control override for their existing Genset ATS systems. Many of these systems are installed in remote properties used for Airbnb type accommodation.
The electrical changeover system runs a 2 Wire Start from the ATS to the generator (close to start & open to stop). Within the ATS module there is often a wiring terminal for an Aux shut down option.
The customer requirement for the SMS Genset ATS project included:
When the mains power fails, the ATS starts the generator as usual.
The generator will now run until mains power is restored as usual.
We then want an SMS text message to be sent to the designated owner notifying them the generator is running.
The designated owner can then decide to stop the generator running if it is not required. Good examples are if it is late at night, the rental property is not occupied, or heating/refrigeration are not currently required. Minimising the time the generator runs will help reduce fuel usage.
When mains power returns the ATS will return to standard operation.
The team established a practical solution that sends the owner a text message “GENSET has turned ON”.
The owner can then turn off the generator if needed, by sending the text message “ON GENSTOP” to the SMS Lite.
The SMS Lite can also turn the generator off for a fixed time.
Sending the text “PULSE GENSTOP 2 HR” stops the generator for 2 hours and then turns it back on. This would be useful to conserve generator fuel whilst preventing appliances like heaters being off for too long and allowing the temperature to drop significantly.
The initial project was using the Kohler VERSO 100 4P ATSS IP31 with 4 poles and a 63A rating.
The Kohler VERSO ATS are a compact solution and are a popular choice in Australia and New Zealand. The SMS Lite interface and solution could also be applied to other ATS.
The SMS Lite provides N/O dry relay contacts rated up for 30V 2A loads. For this application these would drive a similar relay but with an N/C contact. Turning on RLY1 output on the SMS Lite would then open the connection on the slave relay and turn off the unit. This needs to be powered from a stable 12-24V DC (250mA) power source available at all times.
Our engineers were able to sketch this initial wiring design during the discussion with our customer.
