3 phase undervoltage trip device and molded case circuit breaker therewith

Patent metadata

Field	Value
Publication number	US-10614985-B2
Application number	US-201715611926-A
Country	US
Kind code	B2
Filing date	Jun 2, 2017
Priority date	Jan 5, 2017
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

The present disclosure relates to a 3-phase undervoltage trip device capable of automatically tripping a circuit breaker based on an under-voltage of a 3-phase line voltage, including lines to which a 3-phase power is applied. The undervoltage trip device is connected to lines to which a 3-phase power is applied and configured to operate to automatically trip a circuit breaker when an open phase condition occurs on any one of three phases of the power. As the undervoltage trip device automatically trips the circuit breaker when the open phase condition occurs on any one of three phase, occurrence of the open phase condition due to disconnection or an accident on the line may be easily detected.

First claim

What is claimed is:

1. A 3-phase undervoltage trip device comprising:
a rectifier connected to lines of three phases and configured to rectify a 3-phase power applied to the lines and output line voltages of the three phases;
a divider configured to distribute an average voltage of the line voltages of the three phases rectified by the rectifier;
an amplifier configured to amplify the average voltage distributed by the divider;
a comparator configured to compare the average voltage amplified by the amplifier with a reference voltage and output an open phase detection signal;
a switch turned on or off according to the open phase detection signal of the comparator and configured to supply a current to an excitation coil for tripping a circuit breaker when turned on; and
an open phase detector enabled by the open phase detection signal output by the comparator to detect a phase having an open phase condition,
wherein the open phase detector comprises:
first and second rectification and division units configured to rectify and divide line voltages of two phases among the line voltages of the three phases; and
a second comparator configured to compare the divided line voltages from the first and second rectification and division units and output a comparison signal indicating a phase having the open phase condition.

2. The 3-phase undervoltage trip device according to claim 1 , wherein the amplifier comprises an OP amplifier, and the switch comprises a MOSFET.

3. The 3-phase undervoltage trip device according to claim 1 , wherein a one line voltage of a one phase among the line voltages of the two phases rectified and divided by the first and second rectification and division units is the same between the first and second rectification and division units, and the first and second rectification and division units divide the line voltages of the two phases with the same resistance ratio.

4. The 3-phase undervoltage trip device according to claim 1 , wherein the second comparator compares the divided line voltage from the first rectification and division unit with the divided line voltage from the second rectification and division unit to identify a higher one among the divided voltages from the first and second rectification and division units.

5. A molded case circuit breaker comprising;
lines to which a 3-phase power is applied; and
a 3-phase undervoltage trip device connected to the lines and configured to automatically trip a circuit when an open phase condition occurs on any one of three phases of the 3-phase power,
wherein the 3-phase undervoltage trip device comprises:
a rectifier connected to the lines and configured to rectify the 3-phase power applied to the lines and output line voltages of the three phases;
a divider configured to distribute an average voltage of the line voltages of the three phases rectified by the rectifier;
an amplifier configured to amplify the average voltage distributed by the divider;
a comparator configured to compare the average voltage amplified by the amplifier with a reference voltage and output an open phase detection signal;
a switch turned on or off according to the open phase detection signal of the comparator and configured to supply a current to an excitation coil for tripping the molded case circuit breaker when turned on; and
an open phase detector enabled by the open phase detection signal output by the comparator to detect a phase having the open phase condition,

wherein the open phase detector comprises:
first and second rectification and division units configured to rectify and divide line voltages of two phases among the line voltages of the three phases; and
a second comparator configured to compare the divided line voltages from the first and second rectification and division units and output a comparison signal indicating a phase having the open phase condition.

6. The circuit breaker according to claim 5 , wherein the amplifier comprises an OP amplifier, and the switch comprises a MOSFET.

7. The circuit breaker according to claim 5 , wherein a one line voltage of a one phase among the line voltages of the two phases rectified and divided by the first and second rectification and division units is the same between the first and second rectification and division units, and the first and second rectification and division units divide the line voltages of the two phases with the same resistance ratio.

8. The circuit breaker according to claim 5 , wherein the second comparator compares the divided line voltage from the first rectification and division unit with the divided line voltage from the second rectification and division unit to identify a higher one among the divided line voltages from the first and second rectification and division units.

Assignees

• Lsis Co Ltd

Inventors

• Park Min-Woo

Classifications

• H02H3/253

  for multiphase applications, e.g. phase interruption · CPC title

• H01H71/123 Primary

  using a solid-state trip unit (circuits H02H) · CPC title

• H01H83/14

  operated by imbalance of two or more currents or voltages, e.g. for differential protection · CPC title

• H01H83/12

  operated by voltage falling below a predetermined value, e.g. for no-volt protection · CPC title

• H01H71/128

  Manual release or trip mechanisms, e.g. for test purposes (two similar push buttons for closing or resetting and opening or tripping H01H71/58; test switches for earth fault circuit breakers H01H83/04) · CPC title