Detection of capacitor bank fuse/switch failure
AssigneeBeckwith Electric Co., Inc.
InventorMurty Yalla
Life of this patent
Estimating the term…
Abstract
A method for detecting the operating condition of each phase of a three-phase capacitor bank in a power distribution system, including the steps of, if the RMS neutral current is above the bank status closed setting, comparing the phase angle of neutral current (IN) with respect to voltage on one of the phases (VA, VB or VC) and sending an alarm signal when the comparison of the phase angle of neutral current with respect to the phase voltage differs appreciably from the expected phase angles.
Claims6
A method for detection of the operating condition of each phase of a three-phase capacitor bank in a power distribution system, comprising the steps of:
- measuring one of the phase voltages (VA, VB or VC) and the neutral current in the capacitor bank;
- comparing a RMS neutral current with all open (bank status open) and all closed (bank status closed) settings to determine if all the three phases of the capacitor bank are open or closed;
- if the RMS neutral current is above the bank status closed setting, comparing the phase angle of neutral current (IN) with respect to voltage on phase A (VA), or phase B (VB) or phase C (VC);
- sending an alarm signal when the comparison of the phase angle of neutral current (IN) with respect to the phase voltage (if VA is used add 0° , if VB is used add 120° or for VC add) 240° differs appreciably from the phase angles indicated in the following chart:
- Phase angle of IN with respect
- to VA (If VB is used add
- OPEN/CLOSE state of each Phase
- 120° or for VC add 240° to
- A
- B
- C
- the angles shown below)
- OPEN
- OPEN
- OPEN
- N/A
- CLOSE
- OPEN
- OPEN
- 90°
- OPEN
- CLOSE
- OPEN
- −30°
- OPEN
- OPEN
- CLOSE
- 210°
- CLOSE
- CLOSE
- OPEN
- 30°
- OPEN
- CLOSE
- CLOSE
- 270°
- CLOSE
- OPEN
- CLOSE
- 150°
- CLOSE
- CLOSE
- CLOSE
- N/A.
An apparatus for detection of the operating condition of each phase of a three-phase capacitor bank in a power distribution system, comprising in combination:
- a voltage meter for measuring one of the phase voltages (VA, VB or VC) and a current meter for measuring the neutral current in the capacitor bank;
- a controller for comparing a RMS neutral current with all open (bank status open) and all closed (bank status closed) settings to determine if all the three phases of the capacitor bank are open or closed and if the RMS neutral current is above the bank status closed setting, then opening or closing each phases when required while comparing the phase angle of neutral current (IN) with respect to voltage on phase A (VA), or phase B (VB) or phase C (VC) and when the comparison of the phase angle of neutral current (IN) with respect to the phase voltage (if VA is used add 0°, if VB is used add 120° or if VC is used add 240°) differs appreciably from the phase angles indicated in the following chart:
- Phase angle of IN with respect
- to VA (If VB is used add
- OPEN/CLOSE state of each Phase
- 120° or for VC add 240° to
- A
- B
- C
- the angles shown below)
- OPEN
- OPEN
- OPEN
- N/A
- CLOSE
- OPEN
- OPEN
- 90°
- OPEN
- CLOSE
- OPEN
- −30°
- OPEN
- OPEN
- CLOSE
- 210°
- CLOSE
- CLOSE
- OPEN
- 30°
- OPEN
- CLOSE
- CLOSE
- 270°
- CLOSE
- OPEN
- CLOSE
- 150°
- CLOSE
- CLOSE
- CLOSE
- N/A.
Dependencies are inferred from the claim text.