Chapter 3: Operations

Modes of Operation

The Sentry Rack-Mount Fail-Safe Transfer Switch is designed to operate in the following modes:

•Normal

Infeed A provides power to branches A1 & A2 and Infeed B provides power to branches B1 & B2. Each infeed is monitored individually for voltage and current.

•Input Failure

The equipment powered by the failed input is transferred to the remaining input. The input current LED display of the failed input will be blank and the remaining display will report the total current load for the unit.

•Recovery from Input Failure

When voltage is restored to the failed input and remains within ±7% of nominal for 2 seconds, the equipment normally supported by that input is transferred back returning the Sentry to a ‘Normal’ mode with the input current LED displays reporting the total current load for each respective infeed.

•Brownout/Over-Voltage

When an input’s voltage varies from its nominal by ±13% or more, the equipment powered by that input is transferred to the remaining input. The input current LED display of the input in the brownout/over-voltage state will be blank and the remaining display will report the total current load for the unit.

Nominal Voltage*

Brownout

Recovery Voltage

Over-Voltage

100V

87.0V

93.0V

107.0V

113.0V

110V

95.7V

102.3V

117.7V

124.3V

115V

100.0V

106.9V

123.0V

129.9V

120V

104.4V

111.6V

128.4V

135.6V

208V

181.0V

193.4V

222.6V

235.0V

220V

191.4V

204.6V

235.4V

248.6V

230V

200.1V

213.9V

246.1V

259.9V

240V

208.8V

223.2V

256.8V

271.2V

*Nominal operating voltage is configured by the Voltage Selector Switch.

•Recovery from Brownout/Over-Voltage

When the input’s voltage returns to and remains within ±7% of nominal for 2 seconds, the equipment normally supported by that input is transferred back returning the Sentry to a ‘Normal’ mode input current LED displays reporting the total current load for each respective infeed.

•Critical Brownout

A critical brownout is when an input’s voltage drops below its nominal by -25%.

•When an input is already in a brownout/over-voltage state AND the remaining input experiences a critical brownout, ALL equipment will be transferred to the input only experiencing a brownout/over-voltage.

•When an input has already failed AND the remaining input experiences a critical brownout, ALL outlets will turn off.

•Recovery from Critical Brownout

When the input’s voltage returns to and remains within ±7% of nominal for 2 seconds, the equipment normally supported by that input is transferred back.

8 • Operations

Rack-Mount Fail-safe Transfer Switch

 

Installation and Operations Manual