FAS-115DG  Synchronisation & circuit breaker closing

The FAS-115DG synchroniser is applied for synchronisation of a generator to the busbar and closing of its circuit breaker when the voltage difference, the slip frequency and the phase angles are within the preset limits. The synchroniser can be applied in conjunction with a wide range of prime movers, as its control pulses may be set to fit several types – from slowly reacting diesel engines to swiftly reacting gas turbines.
Function
The FAS-115DG performs a dynamic synchronisation, ensuring that the slip frequency is always positive to prevent reverse power conditions from occurring (see option D). Furthermore, the FAS-115DG is provided with relay outputs for controlling the AVR for voltage matching. In order to calculate when to transmit the closing signal to the generator breaker, the synchroniser measures the actual slip frequency and compares this with the circuit breaker closing time (potentiometer marked BREAKER). When the slip frequency and the voltage deviation are within the settings (potentiometers marked FREQ and VOLTAGE), the above calculation is performed, and the synchroniser transmits the closing signal to the breaker “x” degrees before top allowing time for this to close.
In case of harmonic distortion or noise on the voltage inputs, the FAS-115DG is equipped with special filters on the AC voltage inputs to avoid imprecise synchronisation pulse being transmitted. Furthermore, a df/dt (ROCOF) function is implemented. If the filters are unable to make the necessary filtering of the input signals, the df/dt function will prevent imprecise synchronisation pulse from being transmitted. If the df/dt function is active, the situation will be indicated by a flashing ∆f
LED (see option C).