The AR/ARD relays are electromechan-ical convertible contact relays. Earlier relays do not necessarily incorporate all the features described. The Delta ARD4 User Guide is designed as a. Smart Motor Protector ARD2 Series (hereinafter referred to as Protector) utilizes advanced single chip technology and is featured in the strong anti-interference, stable and reliable running, digitalization, intelligence and networking. The protector can protect the motor from timeout startup. The ARD3M intelligent motor protector is suitable for low-voltage motor circuits with rated voltage up to 660V and integrates protection, measurement, control, communication, operation and maintenance. AR. Shop Now ARD Series Motor Protection Relay.