Seismic Switch is pleased to introduce the Seismic Switch Battery Backup Rev. B for monitoring an earthquake seismic sensor even during loss of AC power.

The most important new feature of the Rev. B unit is the red LED that lights up when the battery level is low. When that LED is lit, batteries should be replaced ASAP. If AC power is lost when the red LED is on, the unit will go into seismic trigger mode.

The need for this unit became apparent in the October 17, 1989 Loma Prieta earthquake. In some areas utility power failed before the earthquake shock arrived. Although earthquake seismic detectors did trigger, there was no active control circuitry to receive their output signals. Therefore, potentially damaged elevators were allowed to resume normal operation once power was restored, because the elevator control system did not remember that an earthquake had occurred during the power outage. The stronger the earthquake, the more widespread these types of power outages.

The Seismic Switch Battery Backup Rev. B eliminates this problem by providing reserve power to set an on-board latching relay if a seismic event occurs during the power outage. The latching relay remembers that the earthquake happened. When power is restored, the elevator controller receives the stored seismic trigger signal and enters its earthquake operating mode until a mechanic can inspect the elevator and reset both the controller and the Battery Backup Unit.