Abstract: A thermostat or other in-line, two-conductor control device employs a power-stealing technique to obtain DC power for its electronic controls where the thermostat wire run has an R wire but no C (common) wire. The controlled switch for a reactive load, such as the gas valve relay or compressor contactor, is formed of a pair of power capacitors and a pair of switching transistors or other electronic controlled switches. The conductors for feeding DC power to control electronics are connected with the junctions of the power capacitors and their respective switching transistors. The power capacitors and switching transistors can be configured in respective series combinations, with the series combinations forming a parallel combination.

Abstract: A thermostat or other in-line, two-conductor control device employs a power-stealing technique to obtain DC power for its electronic controls where the thermostat wire run has an R wire but no C (common) wire. The controlled switch for a reactive load, such as the gas valve relay or compressor contactor, is formed of a pair of power capacitors and a pair of switching transistors or other electronic controlled switches. The conductors for feeding DC power to control electronics are connected with the junctions of the power capacitors and their respective switching transistors. The power capacitors and switching transistors can be configured in respective series combinations, with the series combinations forming a parallel combination.

Abstract: A thermostat, of the type that employs latching relays to connect thermostat power to the various wires of the thermostat run, has a re-pulse feature that supplies latching pulses at a given interval, e.g., three hours, to ensure that the relays are in their proper state agreeing with the thermostat mode and the room temperature relative to the setpoint(s). In the case that the room air temperature is changing in a manner contrary to the current heating or cooling mode, which may indicate the latching relay has been knocked or bumped and needs to have its proper state re-established, the thermostat microprocessor issues pulses to the latching relay(s) more frequently, e.g., each 30 minutes, and the re-pulses may have a longer pulse width, e.g., increased from 20 ms to 25 ms.

Abstract: A battery powered thermostat senses a battery voltage drop to a low-battery voltage level. At that point, the thermostat microprocessor provides a LOW BATTERY alert message, visible on the thermostat display. If the occupant fails to replace the power cells or does not notice the LOW BATTERY message, when the battery voltage drops further the microprocessor alters the thermostat set points. This reduces the number of heating or cooling cycles per day, and reduces the number of actuations of the latching relays in the thermostat, conserving remaining battery life. At a further drop in battery voltage the set points are changed additionally. Additional functions, such as second level heat, second level cooling, and fan speed, are disabled. The change in heat or cooling cycles induces the occupant to check the thermostat where he or she will notice the LOW BATTERY message.

Abstract: Property-management or lock-setting thermostats have maximum and minimum set points locked in to prevent abuse of management-provided heating and/or air conditioning. An ePROM or similar internal memory device stores heating and cooling limit parameters that are set in by a technician at the time of installation. A plug-in flash memory module contains an unlock code to match the unlock code stored in said ePROM, to unlock the thermostat and allow the settings to be adjusted; when said flash memory module is removed the thermostat reverts to its lock condition. The thermostat can also respond to unusual rates of change of temperature to block furnace or A/C operation temporarily.

Abstract: In an electromechanical relay the core of the relay coil and a corresponding zone of the armature are each provided with a pole face of zig-zag or stair-step configuration. A succession of corresponding edges of the core and armature pole faces concentrate the magnetic flux to increase the initial force on the armature and to limit the closing force as the armature reaches the closed position. The armature bearing is shaped to create a longitudinal wipe motion. The relay exhibits faster and quieter action with less bounce and reduced contact chatter.

Abstract: A relay situated in series between an AC line source and an AC load has a core conductor connected with the fixed N.O. contact, so that load current flows axially through the core of the actuator coil. Alternatively, the fixed N.C. contact may be connected with the core conductor. A plate armature with leaf springs can achieve linear axial action. A sensor connected to leads of a winding of the actuator coil picks up a an induced voltage that is representative of the current supplied to the load. This provides a simple arrangement for monitoring for current level and can be used for measuring power factor or ?? at the load device. In a three phase embodiment, phase imbalance can be detected.