Electrical transmission or interconnection systems – Switching systems – Switch actuation
Patent
1990-12-19
1993-02-02
Beha, Jr., William H.
Electrical transmission or interconnection systems
Switching systems
Switch actuation
340687, H02J 1300
Patent
active
051840260
ABSTRACT:
The circuit includes a capacitor (C1) and a resistor (R1) connected in series and interconnected with the switch to sense which phase of the line to which the switch's wiper is connected. The impedance of the series circuit of C1 and R1 is very high, so that when the switch is open, it appears that the wiper is connected with line B, through moderate impedance Z1. (Z1 could be an auxiliary appliance component, e.g. water valve heater relay, or could be simply a resistor). Of course, when the switch is closed, the wiper is connected directly to line A. The monitoring device is referenced to a voltage which is related to the power line by being a dc drop below the instantaneously higher voltage line. The monitoring device thus requires dc isolation from the switch, as well as an input voltage which is substantially less than the line voltage of the power line. DC isolation is provided by C1, while diodes D1 and D2 clamp the signal to acceptable levels. In fact, in many instances diodes D1 and D2 already exist in the monitoring device itself, obviating the need for these extra components. The clamping action causes a quasi-rectangular wave to be generated at the monitoring device's input. This wave is phase-shifted by 180 degrees when the switch changes state. This is how the switch's state is determined. Capacitor C2, which is optional, can be used to smooth out transients caused by line spikes and other disturbances.
REFERENCES:
patent: 3001120 (1961-09-01), Bereskin
patent: 4559594 (1985-12-01), Sears et al.
patent: 4591728 (1986-05-01), Kruger
patent: 4654774 (1987-03-01), Lemmers
Beha Jr. William H.
Emerson Electric Co.
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