Abstract: An under frequency protection thermostat-type device includes a thermostat-type housing, a transformer, a line under frequency (LUF) detection and measurement module, a microcontroller, and a load switch. The transformer is adapted to be electrically connected to a primary voltage source having a predefined frequency level and disposed within the housing. The LUF detection and measurement module is electrically connected to the transformer and adapted to detect a line under frequency condition from a signal received from the transformer. The microcontroller is connected to the LUF detection and measurement module and is adapted to send a command to disengage and engage an electrical load as a function of a measured frequency of the voltage source over a predefined period of time. The measured frequency is compared to a predefined frequency threshold.

Abstract: A method for detecting line under voltage (LUV) events and initializing load shedding of loads located near the electrical disturbance without customer and utility intervention. In one example embodiment, the LUV detection system samples a primary voltage source at regular time intervals, thereby generating a series of voltage readings, and compares the voltage readings to an under voltage trigger threshold. If an under voltage condition is detected, then an under voltage in-response cycle is initialized that controls the electrical load. When the voltage readings decrease to below a voltage-power fail level, a plurality of load restore counter values are stored in memory before the load is shed from the primary voltage source. A restore response is then initialized after the voltage level rises above a restore value and is maintained above the restore value for an under voltage out-time period.

Abstract: A method for detecting line under frequency (LUF) events and initializing load shedding of loads located near the electrical disturbance without customer and utility intervention is disclosed. In one example embodiment, the LUF detection system measures the time period of each power line cycle and then compares the measured time period to a utility-configurable trigger period. If the cycle length is greater than or equal to the trigger period, a counter is incremented. If the cycle is less than the trigger period, the counter is decremented. If the counter is incremented to a counter trigger, an under-frequency condition is detected and the LUF response either controls the load or temporarily disconnects it. A restore response is initialized after the frequency rises above a restore value and an under-frequency counter counts down to zero.

Abstract: A method for detecting line under voltage (LUV) events and initializing load shedding of loads located near the electrical disturbance without customer and utility intervention. In one example embodiment, the LUV detection system samples a primary voltage source at regular time intervals, thereby generating a series of voltage readings, and compares the voltage readings to an under voltage trigger threshold. If an under voltage condition is detected, then an under voltage in-response cycle is initialized that controls the electrical load. When the voltage readings decrease to below a voltage-power fail level, a plurality of load restore counter values are stored in memory before the load is shed from the primary voltage source. A restore response is then initialized after the voltage level rises above a restore value and is maintained above the restore value for an under voltage out-time period.