Power factor relay

Claim 2

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative of the voltage on and the current in an alternating current power line, means for generating rectangular pulses from the half cycles of one polarity of one of said signals, timing means turned on by the crossing of the zero axis at the trailing edge of each said half cycle of said one polarity of the other of said signals and being adapted to provide an output timing signal a preselected interval after it is turned on, and power factor measuring means receiving said timing signal and said rectangular pulses as inputs for providing a first output when said rectangular pulse is present when said timing signal is received to thereby indicate power factor is outside a preselected band and for providing a second output when said said rectangular pulse is absent when said timing signal is received to thereby indicate that power factor is within said preselected band.

Claim 3

Power factor measuring apparatus in accordance with claim 1 wherein said timing means is selectively adjustable to vary said interval and said one signal is said current signal and said timing means is turned on at the trailing edge of said half cycle of said voltage signal and said measuring means provides a continuous unidirectional first output when lagging power factor is outside said preselected band.

Claim 4

Power factor measuring apparatus in accordance with claim 1 wherein said timing means is selectively adjustable to vary said interval and said one signal is said voltage signal and said timing means is turned on at the trailing edge of said current signal and said measuring means provides a continuous unidirectional first output when leading power factor is outside said preselected band.

Claim 5

Power factor measuring apparatus in accordance with claim 1 wherein said one and said other signals are said current and voltage signals respectively and said measuring means indicates whether lagging power factor is within said preselected band and wherein said timing means is turned on by the crossing of the zero axis by each half cycle of said one polarity of said voltage or said current signal, and including means for generating rectangular voltage pulses from the half cycles of one polarity of said voltage signal and second power factor measuring means receiving said timing signal and said rectangular voltage pulse as inputs for providing a first output when said rectangular voltage pulse is present when said timing signal is received to thereby indicate leading power factor is within a preselected band and for providing a second output when said rectangular voltage pulse is absent when said timing signal is received to thereby indicate leading power factor is outside said preselected band.

Claim 6

Power factor measuring apparatus comprising, in combination, means for deriving voltage anD current signals representative of the voltage on and the current in an alternating current power line, means for generating rectangular pulses from the half cycles of one polarity of one of said signals, timing means turned on by the crossing of the zero axis at the trailing edge of each said half cycle of said one polarity of the other of said signals and being adapted to provide an output timing signal a preselected interval after it is turned on, said timing means including a timing capacitor in series with a time adjusting potentiometer, transistor means for shunting said timing capacitor, and means for turning said shunting transistor means on and off respectively during the half cycles of said one polarity and of the opposite polarity of said other signal, and power factor indicating means receiving said timing signal and said rectangular pulses as inputs for providing a first output when said rectangular pulse is present when said timing signal is received and for providing a second output when said rectangular pulse is absent when said timing signal is received.

Claim 7

Power factor measuring apparatus comprising, in combination, means for deriving voltage anD current signals representative of the voltage on and the current in an alternating current power line, means for generating rectangular pulses from the half cycles of one polarity of one of said signals, timing means turned on by the crossing of the zero axis at the trailing edge of each said half cycle of said one polarity of the other of said signals and being adapted to provide an output timing signal a preselected interval after it is turned on, said timing means including a timing capacitor in series with a time adjusting potentiometer, transistor means for shunting said timing capacitor, and means for turning said shunting transistor means on and off respectively during the half cycles of said one polarity and of the opposite polarity of said other signal, and power factor indicating means receiving said timing signal and said rectangular pulses as inputs for providing a first output when said rectangular pulse is present when said timing signal is received and for providing a second output when said rectangular pulse is absent when said timing signal is received.

Claim 8

Power factor measuring means in accordance with claim 5 wherein said one signal is said current input signal and said means for generating rectangular pulses includes a transistor to whose base said current input signal is applied and which is biased to quickly saturate during said half cycles of said one polarity and to turn off during the half cycles of opposite polarity.

Claim 9

Power factor measuring apparatus in accordance with claim 5 wherein said timing means also includes a unijunction transistor which is triggered when the voltage on said timing capacitor reaches a predetermined potential, a timing output pulse generating transistor normally biased to be conducting, and means responsive to the triggering of said unijunction transistor to turn off said pulse generating transistor to derive said timing output pulse at the collector thereof.

Claim 10

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative of the voltage on and the current in an alternating current power line, means for generating rectangular pulses from the half cycles of one polarity of one of said signals, timing means turned on by the crossing of the zero axis at the trailing edge of each said half cycle of said one polarity of the other of said signals and being adapted to provide an output timing signal a preselected interval after it is turned on, and power factor measuring means including a clocked R-S flip-flop receiving said rectangular pulses on a set input and said timing output pulses on the clock input thereof for providing a first output when said rectangular pulse is present when said timing signal is received and for providing a second output when said rectangular pulse is absent when said timing signal is received.

Claim 11

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative of the voltage on and the current in an alternating current power line, means for generating rectangular pulses from the half cycles of one polarity of one of said signals, timing means turned on by the crossing of the zero axis at the trailing edge of each said half cycle of said one polarity of the other of said signals and being adapted to provide an output timing signal a preselected interval after it is turned on, and power factor measuring means including a clocked R-S flip-flop receiving said rectangular pulses on a set input and said timing output pulses on the clock input thereof for providing a first output when said rectangular pulse is present when said timing signal is received and for providing a second output when said rectangular pulse is absent when said timing signal is received.

Claim 12

Power factor measuring apparatus in accordance with claim 8 and including means for generating rectangular second pulses from the half cycles of said one polarity of the other of said signals and wherein said flip-flop is of the master-slave type and also receives said second rectangular pulses as an input and is responsive to the presence of said rectangular pulses derived from both said current and voltage signals when said timing output signal is received on said clock input to provide said first output and is responsive to the presence of only one of said rectangular pulses when said timing output pulse is received on said clock input to provide said second output.

Claim 13

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving from each half cycle of one polarity of said voltage signal a rectangular voltage pulse having a leading edge at the crossing of the zero axis by said voltage half cycle, means for Deriving from each half cycle of one polarity of said current signal a rectangular current pulse having a leading edge at the crossing of the zero axis by said current half cycle, a timer adapted to provide an output signal a preselected interval after it is turned on and being adjustable to vary said preselected interval, means responsive to said crossing of the zero axis by said half cycle of one of said signals for turning on said timer, and flip-flop means receiving said timer output signal and said rectangular current and voltage pulses as inputs for providing a first continuous output when said timer output signal is received when both said rectangular pulses are present to thereby indicate the power factor is outside a preselected band and for providing a second continuous output signal when said timer output signal is received when one of said rectangular pulses is absent to thereby indicate the power factor is within said preselected band.

Claim 14

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving from each half cycle of one polarity of said voltage signal a rectangular voltage pulse having a leading edge at the crossing of the zero axis by said voltage half cycle, means for Deriving from each half cycle of one polarity of said current signal a rectangular current pulse having a leading edge at the crossing of the zero axis by said current half cycle, a timer adapted to provide an output signal a preselected interval after it is turned on and being adjustable to vary said preselected interval, means responsive to said crossing of the zero axis by said half cycle of one of said signals for turning on said timer, and flip-flop means receiving said timer output signal and said rectangular current and voltage pulses as inputs for providing a first continuous output when said timer output signal is received when both said rectangular pulses are present to thereby indicate the power factor is outside a preselected band and for providing a second continuous output signal when said timer output signal is received when one of said rectangular pulses is absent to thereby indicate the power factor is within said preselected band.

Claim 15

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving rectangular voltage pulses from half cycles of one polarity of said voltage signal, means for deriving rectangular current pulses from half cycles of one polarity of said current signal, timing means adapted to provide a timing output a preselected interval after it is turned on, means for turning on said timing means in response to the crossing of the zero axis at the leading edge of said half cycle of one polarity of either said voltage signal or said current signal, means including a first flip-flop receiving said timing output and said rectangular current pulses as inputs for indicating when lagging power factor is beyond a selected band, and means including a second flip-flop receiving said timing output and said rectangular voltage pulses as inputs for indicating when leading power factor is beyond a selected band.

Claim 16

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving rectangular voltage pulses from half cycles of one polarity of said voltage signal, means for deriving rectangular current pulses from half cycles of one polarity of said current signal, timing means adapted to provide a timing output a preselected interval after it is turned on, means for turning on said timing means in response to the crossing of the zero axis at the leading edge of said half cycle of one polarity of either said voltage signal or said current signal, means including a first flip-flop receiving said timing output and said rectangular current pulses as inputs for indicating when lagging power factor is beyond a selected band, and means including a second flip-flop receiving said timing output and said rectangular voltage pulses as inputs for indicating when leading power factor is beyond a selected band.

Claim 17

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving rectangular voltage pulses from half cycles of one polarity of said voltage signal, means for deriving rectangular current pulses from half cycles of one polarity of said current signal, first and second timing means each of which is adapted to provide a timing output a preselected interval after it is turned on and being adjustable to vary said interval, means responsive to the crossing of the zero axis at the leading edge of said half cycle of one polarity of said voltage and current signals respectively for turning on said first and second timing means, lagging power factor indicating means receiving as inputs said rectangular current pulses and said timing output of said first timing means for providing a continuous output when said timing output is received when said rectangular current pulse is present to thereby indicate that lagging power factor is outside a preselected band, and leading power factor indicating means receiving as inputs said rectangular voltage pulses and said timing output of said second timing means for providing a continuous output when said timing output is received when said rectangular voltage pulse is present to thereby indicate that leading power factor is outside a preselected band.

Claim 18

Power factor measuring apparatus comprising, in combination, means for deriving voltage and current signals representative respectively of the voltage on and the current in an alternating current power line, means for deriving rectangular voltage pulses from half cycles of one polarity of said voltage signal, means for deriving rectangular current pulses from half cycles of one polarity of said current signal, first and second timing means each of which is adapted to provide a timing output a preselected interval after it is turned on and being adjustable to vary said interval, means responsive to the crossing of the zero axis at the leading edge of said half cycle of one polarity of said voltage and current signals respectively for turning on said first and second timing means, lagging power factor indicating means receiving as inputs said rectangular current pulses and said timing output of said first timing means for providing a continuous output when said timing output is received when said rectangular current pulse is present to thereby indicate that lagging power factor is outside a preselected band, and leading power factor indicating means receiving as inputs said rectangular voltage pulses and said timing output of said second timing means for providing a continuous output when said timing output is received when said rectangular voltage pulse is present to thereby indicate that leading power factor is outside a preselected band.