AFB is an innovative ultra high-speed DC circuit breaker based on PLUTON experience and advanced technologies. AFB is provided for application in tram, trolleybus, light rail and metro traction substations power distribution systems.
Application of arc-free interruption concept in DC circuit breaker provides the following significant benefits in comparison with a circuit breaker with standard switching and arc interruption:
Benefits of AFB arc-free circuit breaker in comparison with a circuit breaker with standard switching and arc interruption:
Before circuit breaker tripping control system tests: auxiliaries voltage, high-voltage opening and interrupting capacitors voltage, interrupting thyristors and shunt diodes proper functioning. Closing is possible with preliminary line test and without it.
Pre-charged low-voltage capacitors battery provides circuit breaker closing by closing coil actuation with closing thyristor.
Circuit breaker control system actuates opening thyristor on receiving opening command. When thyristor opens, the power stored in high-voltage opening capacitor is switched to opening coil. The opening coil magnetic field influences opening mechanism, which actuates vacuum interrupter moving contact, thereby vacuum interrupter power contacts open.
Arc starts between vacuum interrupter contacts upon their opening. Pre-charged capacitor with discharge current directed towards load current flow is used for the arc interruption.
Capacitor discharge current is switched in antiphase to the main current of power circuit. The arc is interrupted at the moment, when currents algebraic sum is zero. Afterwards the contacts open and interrupt power circuit.
Emergency opening has similar to operational opening principle. In this case, the signal for opening is measurements from current sensor, installed in the circuit breaker main power circuit, and processed by AFB control system microcontroller according to specified algorithms.
Electrodynamic tripping drive:
Overvoltage protection components:
Control system has built-in adjustable protection functions:
Overcurrent protection is activated upon exceeding of measured current value, setting within the specified time interval.
In case of current preset rate of rise exceed, protection tripps before the setting is reached. Thus, total tripping time is reduced and maximum short circuit current is limited. It helps to significantly reduce the number of substation equipment failures, eliminate contact network cables burn off, overheating and fire caused by overload, etc.
Control and internal monitoring system provides complete all-sufficient control of circuit breaker and its components, and fulfills all necessary functions, including protection, as well as remote control and measurement, etc.: