Abstract: A fault management apparatus and method are described for a system that includes at least one electro-mechanical or electro-hydraulic component, such as a system valve or main discharge pump in a process plant or water transmission line. An actuator is electrically coupled to the component for application of control signals to selectively actuate or de-actuate the component. A standby power supply, in the form of a uninterruptible power supply (UPS) stores sufficient electrical energy to energize the valve and/or the discharge pump to change the states thereof from one operational state to another. The UPS has sufficient electrical capacity to close a system valve to its fail-safe condition. The actuator can be actuated in a number of different ways, including sensing of failure of main power, manual activation or sensing of some emergency condition.

Abstract: A fan control board having a central low voltage wiring center as well as a safety interlock for electric heaters. The interlock uses diodes to insure proper fan operation in the event of miswiring of the heater sequencers. Another feature is a quick connect for the time delay relay which permits easy insertion and removal thereof for replacement and/or cleaning. Diode circuits are provided in both the circuit to normally power the fan motor as well as in the circuit to power the PTC resistor which closes the fan motor circuit with the circuit which powers the PTC resistor also being connected across the fan motor circuit to provided rectified power to the fan circuit and permit the fan motor to turn on concurrently with the application of power to the PTC resistor to prevent the heater from being turned on prior to the fan.

Abstract: A sensing circuit system including circuitry for sensing impedance variations of a variable impedance element. As disclosed, a bridge circuit system includes a bridge circuit to which the variable impedance element is couplable. The bridge circuit system further includes circuitry for detecting open circuit or short circuit fault conditions of the variable impedance element. The variable impedance element is coupled to the bridge circuit by a connector, having two connector components, which is also operable to couple the fault detection circuitry to the bridge circuit only when the two components of the connector are connected together.

Abstract: A control circuit for producing a repetitive closed-circuit, open-circuit condition between an electrical power source, such as a battery, and an electrical load comprises a positive temperature coefficient resistor in series with a relay coil. The PTC resistor is caused to alternate between a low resistance state and a high resistance state which permits energization and de-energization of the relay coil.

Abstract: A lamp is included as a cathode load for a gate-turn-off silicon controlled rectifier (GTO). The conduction path of a transistor is connected between the gate electrode of the GTO and ground. The GTO and lamp are turned off by applying current in the forward direction through the base-emitter junction of the transistor, thereby turning on the transistor and placing the gate electrode of the GTO at ground. The forward current passes through a thermal circuit breaker which periodically opens in response to the heat produced by the current flow, causing the gate electrode of the GTO to become forward biased via the collector load resistance of the transistor and turn on.