US3764904A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Monitor for phase sequence and loss
Assignee: Montgomery Elevator Co
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Filing: 1970-12-07
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Granted: 1973-10-09
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Expires: 1990-12-07
Abstract
Abstract A monitor detects improper phase sequence or phase loss in a three phase system. A thyristor and a series connected relay are directly connected between two line conductors. A network using only two resistors and one capacitor connects all three line conductors to a summing junction connected through a variable resistive path to the gate of the thyristor to continuously actuate the relay when the desired phase sequence rotation is present.
Inventors
- 👤 J Drexler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:58
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/004; G; G01; G01R; G01R29/00; G01R29/18
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
285 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: switching means including thyristor means in series with relay means energized when the thyristor means is in a conductive state and there is no loss of phase in said three phase system for indicating the occurrence of the desired relative phase rotation sequence, the deenergization of said relay means indicating an improper phase sequence or a loss of phase; conductor means connecting said switching means directly between a pair of said three line conductors to cause said relay means to be energized by current flowing through the thyristor means from a pair of phases of said three phase system, said conductor means containing no lumped impedance elements; and network means for actuating said thyristor means to said conductive state, including common means coupled to said thyristor means and developing an enabling signal having a predetermined absolute magnitude during said desired relative phase rotation sequence and a lesser absolute magnitude during said improper phase sequence or said loss of phase, said lesser absolute magnitude being insufficient to gate said thyristor means to said conductive state, first lumped impedance means coupled between a first of said line conductors and said common means, second lumped impedance means coupled between a second of said line conductors and said common means, and third lumped impedance means coupled between a third of said line conductors and said common means, at least one of said lumped impedance means providing a reactive impedance, said impedance means having values to develop said predetermined absolute magNitude when said desired relative phase rotation sequence is present.
Claim 2
Dependent Claim
285 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: switching means including thyristor means in series with relay means energized when the thyristor means is in a conductive state and there is no loss of phase in said three phase system for indicating the occurrence of the desired relative phase rotation sequence, the deenergization of said relay means indicating an improper phase sequence or a loss of phase; conductor means connecting said switching means directly between a pair of said three line conductors to cause said relay means to be energized by current flowing through the thyristor means from a pair of phases of said three phase system, said conductor means containing no lumped impedance elements; and network means for actuating said thyristor means to said conductive state, including common means coupled to said thyristor means and developing an enabling signal having a predetermined absolute magnitude during said desired relative phase rotation sequence and a lesser absolute magnitude during said improper phase sequence or said loss of phase, said lesser absolute magnitude being insufficient to gate said thyristor means to said conductive state, first lumped impedance means coupled between a first of said line conductors and said common means, second lumped impedance means coupled between a second of said line conductors and said common means, and third lumped impedance means coupled between a third of said line conductors and said common means, at least one of said lumped impedance means providing a reactive impedance, said impedance means having values to develop said predetermined absolute magNitude when said desired relative phase rotation sequence is present.
Claim 3
Dependent Claim
32 words
The monitor of claim 1 wherein said at least one lumped impedance means comprises a capacitor providing a capacitive impedance, and the remaining lumped impedance means comprise resistors providing a resistive impedance.
Claim 4
Dependent Claim
41 words
The monitor of claim 1 wherein said common means includes resistor means coupled to a junction between said series connected thyristor means and relay means, the voltage drop across at least a portion of said resistor means forming said enabling signal.
Claim 5
Dependent Claim
43 words
The monitor of claim 4 wherein said resistor means includes a fixed resistor in series with a variable resistor, the voltage drop across said fixed resistor forming said enabling signal, said variable resistor having different selectable resistance values to form a sensitivity control.
Claim 6
Dependent Claim
128 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: switching means having a gate electrode and actuated when a predetermined gating signal is present at said gate electrode; a summing junction; noninductive impedance means coupled between said summing junction and said gate electrode to pass a gating signal to the switching means; and network means for coupling said summing junction to each of said three line conductors, comprising first resistive means coupled between said first line conductor and said summing junction, capacitive means coupled between said second line conductor and said summing junction, and second resistive means coupled between said third line conductor and said summing junction.
Claim 7
Dependent Claim
128 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: switching means having a gate electrode and actuated when a predetermined gating signal is present at said gate electrode; a summing junction; noninductive impedance means coupled between said summing junction and said gate electrode to pass a gating signal to the switching means; and network means for coupling said summing junction to each of said three line conductors, comprising first resistive means coupled between said first line conductor and said summing junction, capacitive means coupled between said second line conductor and said summing junction, and second resistive means coupled between said third line conductor and said summing junction.
Claim 8
Dependent Claim
43 words
The monitor of claim 5 wherein said three phase system has a predetermined frequency, the resistance values of said first and second resistive means and the capacitance value of said capacitive means being selected to produce approximately equal impedances at said predetermined frequency.
Claim 9
Dependent Claim
30 words
The monitor of claim 6 wherein said first resistive means comprises a single resistor, said second resistive means comprises a single resistor, and said capacitive means comprises a single capacitor.
Claim 10
Dependent Claim
14 words
The monitor of claim 5 wherein said noninductive impedance means comprises solely resistive means.
Claim 11
Dependent Claim
182 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: three terminal switching means having first and second terminals with conductive and nonconductive states therebetween under control of a gate signal at a control terminal; relay means for changing the state of contact means when a predetermined current is coupled through a relay coil; conductor means connecting said first and second terminals and said relay coil in series between a pair of said three line conductors; means for summing the three relative phases including a first resistive means connected to a first of said line conductors, capacitive means connected to a second of said line conductors, and a second resistive means connected to a third of said line conductors; resistive means connected between said summing means and said conductor means to develop at a junction therein a voltage drop proportional to current flow through the resistive means; and noninductive means for connecting said control terminal to said junction in said resistive means.
Claim 12
Dependent Claim
182 words
In a three phase system having three line conductors with a desired relative phase rotation sequence, a monitor for detecting an improper phase sequence or a loss of phase, comprising: three terminal switching means having first and second terminals with conductive and nonconductive states therebetween under control of a gate signal at a control terminal; relay means for changing the state of contact means when a predetermined current is coupled through a relay coil; conductor means connecting said first and second terminals and said relay coil in series between a pair of said three line conductors; means for summing the three relative phases including a first resistive means connected to a first of said line conductors, capacitive means connected to a second of said line conductors, and a second resistive means connected to a third of said line conductors; resistive means connected between said summing means and said conductor means to develop at a junction therein a voltage drop proportional to current flow through the resistive means; and noninductive means for connecting said control terminal to said junction in said resistive means.
Claim 13
Dependent Claim
69 words
The monitor of claim 9 wherein said voltage drop exceeds a predetermined switching value when said desired relative phase rotation occurs at said three line conductors, said voltage drop gating said switching means into said conductive state to cause said conductor means to pass said predetermined current to said relay coil, whereby the changed state of said contact means indicates the occurrence of the desired relative phase rotation sequence.
Claim 14
Dependent Claim
34 words
The monitor of claim 10 wherein said resIstive means includes a variable resistor manually adjustable to difference resistance values to change the voltage drop at said junction, said variable resistor forming a sensitivity control.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |