There are several solutions to assure the safety and efficiency of the machines used in industries. However, the demand for quality products that integrate efficiently in the system is higher every day. Thinking of that, WEG has developed a line of intelligent equipment which stands out for its ability to communicate with the fieldbus.

WEG launched the SRW01 Intelligent Relay with the purpose of facilitating the command and protection of electric motors in industries of a wide range of segments. The equipment is capable of supervising systems of low voltage single-phase or three-phase AC electric motors with up to 840 A.

Practical and versatile, the equipment has a modular design and reduced size – 45mm wide and 100mm high. Moreover, its functions are: protection, control, measurement, monitoring and diagnosis. The great differential is the ability of interconnection in communication networks which support the three main communication protocols: ProfiBus – DPV1, ModBus – RTU and DevicNet. The SRW01 has a communication plug-in unit –plug and play technology – which makes the exchange of protocol by the user easy. It also has a USB drive which allows the monitoring of the system and of the temperature memory capable of maintaining the thermal image of the motor even without energy.

The SRW01 can be programmed by the user according to his needs by using the WLP software distributed free of charge with the product or through the site The modular design allows more flexibility in the integration to the system since the control unit (CU) can be installed next to the measuring and current unit (MCU) forming a single unit or assembled separately at a distance of up to two meters. This characteristic is very useful to the mills that need to save space and guarantee the organization of their structure without interfering with the production. The power voltage range of the SRW01 is of 110 to 240Vac/Vdc. The SRW01 – Control Unit has leds which indicate the status of each input and output and others that show the status of the fieldbus, the operation conditions and the fault status (TRIP) or alarm.


The SRW01 has self-programmable operation modes which allow the user to select with which mode he wants to operate. Given this information, the relay automatically sets to the digital inputs and outputs according to the selected operation mode. This alternative can be applied on three-phase motors such as direct starters, reversal or star-delta switches or also as starters in Dahlander and Two Winding motors, besides the PLC mode (remote I/0).

All modes allow monitoring of the motor. The transparent mode guarantees the user more flexibility in the applications allowing access to all the digital inputs and outputs of the relay besides the possibility of creating his own application softwares.

The diagnoses given by the relay are very useful for maintenance and measurements. The results can be seen on the WLP or HMI. The SRW01 offers several options of monitoring such as that of digital inputs and outputs, RMS current of each phase, motor frequency, number of trips per type of faults or number of startings, the hours of operation of the motor or relay and the level of phase unbalance. And, because only monitoring is not enough, the SRW01 also has protection functions against overload, thermal protection, phase fault or current unbalance between phases, undercurrent or overcurrent and locked rotor, internal ground fault and out of range frequency.