Servers Room Controller
The customer have a big server room with six air conditioners but only two of them should be working at any given time. Also, he wanted to get an alert if the temperature in the server room rise.
A controller with a cellular modem, six relays (to control the air conditioners) and two temperature sensors that were installed in two different locations in the server room.
Technical description of the controllers and the development:
The controller activates the air conditioners using contactors. It is programmed to turn on two air conditioners in a circular rotation every 24 hours (parameter that can be change by the customer).
In addition, each of the sensors can be configured with a maximal temperature threshold, when met, will make the controller to turn on all six air conditioners and will send an alert via SMS.