Application

Our DZ15LED 10-40A  50-100A  100-250A/3902□ type multifunctional auto protective switch is mixed with the protection functions of phase failure, over-current, short circuit faults, able to provide the automatic protection for the motors under AC 380V, 50Hz, also used to start motor non-frequently, further to some degree, prevent the accident of distribution transformer destroyed resulted from over-current because motors run at failure of one phase caused one phase of drop out fuse melted down.The merit of this switch has solved the problem that many switches can't take action while the one phase of drop out fuse is melted down, no matter drop out fuse melted down, low voltage fuse burnt, one phase of three phase motor is broken, which make it run at phase absence, it can perform the effective protection

Structure and working principle

This protective switch is a comprehensive switch for motor with fast response, all parts assembled in bakelite shell. (Working theory as picture 1)

The signal of phase failure come from three series connected CTs.

When the motor run at phase absence, the CT will output a signal of phase failure, to touch off electric trigger and drive release to open the switch, consequently protect the motor.

When motor happen to over-current or short circuit, the o/c release will drive switch to open the line, (o/c and s/c releases have two kinds: electronic type and hydraulic type), namely protect the motor.

Normal operating conditions

Altitude: not higher than 2500m 

No place rain and snow erosion;

No explosive medium and no corrosion and damage the insulation of gas and conductive dust areas.