Load control switch
Most load control switches consist of a communication module and the relay switch and can be used as part of a demand response energy efficiency system such as a smart grid. Such a switch operates similarly to a pager, receiving signals from the power company or electrical frequency shift to turn off or reduce power to the appliance during times of peak electrical demand. Frequently, the device has a timer that will automatically reset the switch back on after a preset time. Some operationally intolerant appliances, such as dryers, use switches that can reduce or shut off power to their heating coils yet still tumble until signaled to resume full power.
Most load control switches have only one-way communication, receiving signals from the power company. Some are now two-way, which helps the power company locate faulty load control switches. In a dynamic demand mode the switches are stand alone at the appliance and turn off independently by monitoring the grid without receiving signals. Many electric cooperatives offer free installation of load control switches to their members, sometimes with incentives.
Load control switches can be a powerful tool to prevent brown-outs and black-outs when electricity storage, transmission, or generation resources are insufficient. It allows the electric companies to respond to emergencies without shutting off all power to customers. They also reduce costs for electric companies by reducing the amount of expensive electricity they need to buy from other companies during peak demand.