Circutor sa of spain manufactures microprocessor based synchro 96 relay which is able to measure and control the connection of an auxiliary generator to the electrical mains bus. Synchro 96 measures the two frequencies [calculating the difference] and the phase shift between the two supplies and gives correcting signals to the speed governor of the incoming generator. The voltage is a less critical parameter for the connection of the generator and hence an acceptance signal can be given to the instrument, by a separate voltage comparator, if necessary. The unit incorporates: two regulating relays for frequency increase/decrease; control of on/off periods of the regulating relays; adjustment of limit of phase shift; and, adjustment of delay time for breaker closure. The unit is in a standard 96 x 96 mm square housing and its front plate has a circular visualization, consisting of 10 leds, giving approximate information about: 1 ] the frequency difference- circular movement of the leds means a difference in frequency. The speed and the direction of movement are proportional to this difference. 2] the phase shift angle-in case the frequencies are equal, one led will keep lit on indicating the approximate phase shift. 3] state of the output contacts-a sign + and-will light each time the speed increase and decrease relays are activated. 4] synchronisation signal-a synchronization sign in the upper part of the scale will light when the synchronization conditions are reached. Thus the unit has the advantages of visualization, making it easier to use and is very economical.
