DC board

DC boards provide the following functions:

• electric power input with necessary voltage and power level irrespective of main network condition from accumulator batteries (hereinafter AB) with recharging from charging and recharging units;
• electric power distribution consumers;
• uninterrupted power supply of consumers supply circuits;
• selective overload currents and short circuit protection of inputs and outgoing lines;
• supply and power distribution system duplication with bus sectioning;
• continuous automatic voltage monitoring on DC board busbars with voltage deviation from rated value signal forming;
• continuous automatic monitoring of DC network insulation resistance to earth with insulation resistance drop below acceptable level signal forming;
• local and central signaling;
• accumulator battery current measurement with analogue or digital ammeter, accumulator battery and main busbars voltage measurement with analogue or digital meter providing also measuring transducer function (output voltage 0…10 V).

Automatic withdrawable, plug-in and fixed circuit breakers produced by Schneider Electric (France), ABB (Germany) or other manufacturers can be applied for DC board cabinets.

To prevent accidental contact with live parts outgoing lines automatic circuit breakers are installed behind rotating frames in cabinet middle section behind external doors. Up to 12 three–pole circuit breakers or up to 20 two–pole modular circuit breakers can be installed in one line DC board cabinet.

Molded-case automatic circuit breakers with high shock and vibrations resistance provide electromagnetic compatibility and allow application in tropical climate.

Benefits of automatic circuit breakers applied in DC boards:

• molded-case with high shock and vibrations resistance providing reliability and long lifetime;
• ensure guaranteed electromagnetic compatibility;
• can be applied in tropical climate.

Main features:

• double insulation, complete separation of power and auxiliary circuits;
• selectivity that allows selecting only fault area, providing maximum uninterrupted operation;
• circuit-breaker operation doesn’t depend on pressure and closing speed;
• access to arc chutes, moving and fixed contacts is provided by simple removal of circuit breaker cover that quickens maintenance and increases safety.

DC board can be equipped with microprocessor control system.

Furthermore, industrial controller is installed in one of DC board cabinets, providing receipt and transmission of data on all main circuits switching devices state and network parameters into remote control system, as well as transmission of signals from operator for drive equipped switching devices closing and opening.

Analogue or digital current and voltage monitoring measuring devices can be installed in line cabinets (digital devices can be equipped with RS-485 interface for measurement values output into remote control and automation system).

Bender GmbH (Germany) devices provided for operation in DC isolated networks, are applied for DC boards insulation monitoring. Measured insulation resistance is continuously displayed on LCD screen.

Front panels with color symbolic circuit corresponding to set of switching equipment for each cabinet and visual color LED position indicators (on/off) of switching devices are located on the doors of switchgears. It allows operational staff to be easily informed about condition of power supply circuits of metro power consumers.