Crouzet 84872501 hsv frequency monitoring relay ip20 30 crouzet 84872501 this hsv frequency monitoring relay from crouzet has been designed to control its own supply voltage connected between phase and neutral equipped with a host of excellent features including over and under frequency with two independent relay outputs selectable latching memory function led status indication and ip30 casing ip20 terminals protection crouzet 84872501 hsv frequency monitoring relay