Arc flash protection

The arc flash protection is available on the optional hardware

module. The module supports connection of up to four sensors.

The sensors can be of lens or loop types, or a free mixture. Both

sensor types are supervised against sensor failure. Fast tripping

increases staff safety and limits material damage, therefore it is

recommended to use static power outputs (SPO) instead of

normal power outputs (PO). This typically decreases the total

operating time with 4..6 ms compared to the normal power

outputs.

Measurements

The base functionality of the REX640 relay contains a number of

basic measurement functions for current, voltage, frequency,

symmetrical components of currents and voltages, power,

power factor and energy. These measurement functions can be

freely connected to the measured secondary quantities

available in the relay. The relay can also measure various analog

signals via RTD and mA inputs. All these measurements can be

used within the relay configuration for additional logics. The

measurements are available locally on the HMI and can be

accessed remotely via communication. The information is also

accessible via Web HMI.

The relay is also provided with a load profile recorder. The load

profile feature stores the selected load measurement data

captured periodically (demand interval). The records can be

viewed on the LHMI and are available in COMTRADE format.