The emergency power control unit - type 79239

We recently serviced an Auto-Maskin control unit for emergency power, that was developed in the year 1979. This, for its time pretty sophisticated, 40-year old vintage control unit was simply named the “79239”. “79” implies the year it was developed, and “239” was the current drawing number that year.

At the time, Auto-Maskin had an ongoing supply of emergency power systems for hospitals, schools, greenhouses, water pumps, etc. and needed a standardised control panel. Before the development of the 79239, such systems were realised with relay logic and components.

At the time it was developed, the 79239 had some pretty sophisticated functionality. It was a full-blown fully automatic control panel for emergency power, with monitoring of key genset parameters. It would monitor all three voltage phases of the grid and generator with adjustable setpoints, it had three start attempts for the genset and even a built-in Test functionality. The latter would simulate a grid failure, then automatically start the genset and connect its power to the load.

During the genset operation, the 79239 would monitor its oil pressure, coolant temp, generator voltage, etc. and also guard against over-current. Upon finishing the test, the operator simply pressed AUTO and the 79239 re-connected the grid to the load, ran the genset for a predefined cooling sequence and stopped it.

In it for the long-run!

The 79239 standardised emergency power control unit became very popular in the domestic market, and several hundred units were supplied.

It is unknown how many that are still in operation, but Auto-Maskin can do repair work, and we find joy in putting them back into service.

We still have the knowledge, documentation and willingness to support them.

– And the unit being serviced?

Even after 40 years, it was operating flawlessly and should still have many years of service ahead of it.