- OUT OF PRODUCTION -

The relays series DTR are intended for the complete protection of high power motors, with medium voltage or low voltage supply. Several protection functions, incorporated in a single relay, assure the operation against different fault conditions: over-heating caused by a mechanical overload or by an abnormal supply, locked rotor, too long starting, interruption of one supply conductor, current unbalance, short circuit between phases, short circuit between turns, earth fault, underload running. The thermal protection is a total memory type, so as to take care of the real heating condition of the motor; a light bar indicator shows the operator the load condition of the thermal replica unit.
A thermal prewarning setting gives a helpfull information to take actions before a possible trip of the protection and to inhibit too frequent startings of the motor. The short circuit protection can be switched off, as required in case of motors controlled by contactors and protected by fuses. The circuit for the residual current protection can be connected to a ring type summation transformer or to the common of three line CT's; all the other protection functions are supplied by two phase CT's.