Self-compensating voted logic power interface with tester

A protection system is described for a nuclear reactor comprising: redundant sets of sensors for monitoring preselected reactor parameters and operating conditions and for generating redundant partial actuation signals in response to preselected values and conditions; three independent logic trains, to each of which each redundant partial actuation signal is applied, the logic trains each generating an actuation signal in response to a preselected number of the redundant partial actuation signals; a load; a voltage source; three pairs of switches connected in three groups of two switches each with the two switches in each group associated with a different pair of switches and being connected in series, and with the three groups of switches being connected in parallel with each other and in series with the load across the voltage source; means for applying a different one of the actuating signals independently to each of the pairs of switches to actuate the same, and thereby actuate the load, when two out of the three actuation signals are generated; a resistor shunting each switch to provide a leakage path through each group of switches, the impedance of the resistors being several magnitudes larger than that of a closed switch such that the current through the leakage paths is insufficient to energize the load; detector means connected to each group of switches and responsive to the change in impedance produced by actuation of a resistor shunted switch in the group to provide a digital signal having a first value when neither of the switches in the group is actuated and a second value when at least one of the switches in the group is actuated; and test means for selectively generating actuating signals and for monitoring the detector means for preselected patterns of the digital signals