The first key parameter discussed here is VR or VRWM. The subscript RWM stands for reverse working maximum. Usually called the reverse stand off voltage, it is the maximum voltage that can be applied to the ESD protector without actually activating the device. The device VRWM should be equal to, or greater than the peak operating voltage of circuit being protected. This is to ensure that the protection device does not clip the normal circuit operating or signal voltage. So this parameter does not describe a protection aspect of the TVS diode array. Rather, it serves only to make sure the array does not interfere with the system in normal operation.