Application 

This series of mining flame-proof low voltage side guard box for movable transformer substation (shortened for guard box below) is applicable in explosion danger coal mine downhole filled with methane and coal dust, installed at low voltage side of movable transformer substation, together with our owned KJG series mining flame-proof intrinsic safety high voltage vacuum distribution device, compose ideal movable transformer substation system with low voltage fault breakdown high voltage function. To supplying power system with 3300V, 1140V, 660V, 380V/50Hz, rated current below 1250A, have electricity leakage, leakage closedown, short circuit, overload, phase balance, wind electricity closedown etc. Protection functions. It can automatically cut off power when supplying power circuit have overload, short-circuit, loss of phase or electricity leakage. As main switch, it has three-phases Symmetry leakage and leakage closedown protection, also is reserved protection for branch switch leakage protection. Over-current protection have Normal inverse special characteristics, Proximal output short-circuit adopt no voltage releasing big current protection circuit.

Features 

This guard box adopts both sides coil out, fulfill multiplex load connection.

All fault drive high voltage side breaker to break down through signal cable, to decrease break-down current, overcome low voltage side switch frequent break-down fault of movable transformer substation, also overcome the dead zone problem which is that electricity leakage of the loop from transformer low voltage winding group to low voltage feeding switch could not break down fault point, can match with different types movable transformer substation.

Automatically following voltage change, free jumper design, no need to change periphery electricity circuit, make customers to use conveniently.

Either switch is opened or closed, online thousand ohms meter can indicate current insulation state all the time, convenient to advanced maintenance and adjustment networks insulation degree.

Main technical parameters 

Rated working voltage: 3300V, 1140V, 660V, 380V.

Rated working system: permanent working.

Cable O.D.: main loop Φ42-Φ78; control loopΦ9-Φ23.

Size (L×W×H): 574×882×732.

Rated working current: 50 to 1250A.