GB2101430A - Overload monitor for electrical machines - Google Patents

Overload monitor for electrical machines Download PDF

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Publication number
GB2101430A
GB2101430A GB08215134A GB8215134A GB2101430A GB 2101430 A GB2101430 A GB 2101430A GB 08215134 A GB08215134 A GB 08215134A GB 8215134 A GB8215134 A GB 8215134A GB 2101430 A GB2101430 A GB 2101430A
Authority
GB
United Kingdom
Prior art keywords
current
machine
monitoring
square
direct current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08215134A
Other versions
GB2101430B (en
Inventor
Hans-Hagen Heine
Manfred Schoenen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vodafone GmbH
Original Assignee
Mannesmann AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mannesmann AG filed Critical Mannesmann AG
Publication of GB2101430A publication Critical patent/GB2101430A/en
Application granted granted Critical
Publication of GB2101430B publication Critical patent/GB2101430B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G01R31/343—Testing dynamo-electric machines in operation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/0811—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors for dc motors

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Control Of Electric Motors In General (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Control Of Direct Current Motors (AREA)
  • Fuses (AREA)
  • Control Of Voltage And Current In General (AREA)

Abstract

In a method of monitoring the effective current in direct current electrical machines to prevent overloading, a quantity representing the actual current (Iist) is squared; and a quantity representing the square of the rated current (I<2>N) is subtracted from the square of the actual current (I<2>ist). The difference is integrated over time, and the integrated value is indicated as a measure of the loading of the drive. This measurement may be used to control the load. <IMAGE>

Description

SPECIFICATION A method and overload safety device for the monitoring of the effective current in direct current electrical machines The invention relates to the monitoring of the effective current in direct current electrical machines to prevent overloading, and an electronic overload safety device therefor.
The monitoring of the effective current in direct current electrical machines has to date been carried out if at all, in complicated electronic calculating circuits. This mode of operation was only capable of being carried out with costly equipment and installations. The setting of these installations was very time-consuming, since for the operation a series of initial data on the installation to be monitored has to be ascertained.
The present invention seeks to prevent overloading of direct current electrical machines by monitoring of the effective current therein. By monitoring the effective current, the load of the drive can be established and the drive protected from overloading.
According to the invention a method of monitoring the effective current in a direct current electrical machine comprises squaring a first quantity representative of the actual current; subtracting therefrom a second quantity representative of the rated current; and integrating the difference over time, the integration being indicated as a measurement for the loading of the machine. Normally, the first and second quantities are respectively the actual current and the square of the rated current. The integration can be used to control the load on the machine.
An overload safety device according to the invention comprises a squarer for squaring a first quantity representative of the actual current; means for generating a second quantity representative of the square of a rated current for the machine; a subtractor connected to the squarer and the generating means and operative to subtract said second quantity from said first quantity; and an integrator connected to the output from the subtractor for integrating such subtraction with respect to time, and which is connected to a display unit for indicating a measurement for the loading of the machine. A threshold value monitor may be included, for indicating when said measurement reaches a predetermined value.
According to the invention, starting from the rated current of the machine, there is a simple, uncomplicated monitoring with a very high information content for the operator of the installation. Further, the invention enables an effective security against overloading to be established.
The invention will now be described by way of example and with reference to the accompanying drawing which shows a block diagram of a device embodying the invention.
In the system illustrated, the actual current (1iso) is fed into a squarer 1, and is squared. Connected with the squarer 1 is a subtractor 3, in which the square of the rated current (12N) iS deducted from the square of the actual current (12,5t). The square of the rated current (12N) iS fed to the subtractor 3 from a constant voltage source 2.
When a positive difference occurs (1215t12N > O) the difference is accumulated in an integrator 4 over time. The content of the integrator 4 is shown in the display 7. The value indicated there is a measurement for the time, which must be evaluated, until the monitored machine can be loaded again. At the same time the content of the integrator 4 is compared in an electronic threshold value monitor 5. With a value of < 0, the signal is given, by way of an optical or acoustic indicator, here a signal lamp 6, that the machine is ready to operate.
With a value of > 0, the re-starting of the machine should not take place because of the risk of a thermal overload, until the value has become =O or < 0 after a pause. For this, an automatic reclose blocking can be provided.
The operation of the circuit shown is also obtainable with modules of digital technology.
Claims
1. A method of monitoring of the effective current in a direct current machine to prevent overloading, comprising squaring a first quantity representative of the actual current; subtracting therefrom a second quantity representative of the rated current; and integrating the difference over time, the integration being indicated as a measurement of the loading of the machine.
2. A method according to Claim 1 wherein the integration is used to control the load on the machine.
3. A method according to Claim 1 or Claim 2 wherein the first and second quantities are respectively the actual current and the square of the rated current.
4. A method of monitoring the effective current in a direct current electrical machine substantially as described herein with reference to the accompanying drawing.
5. An electronic overload safety device for direct current electrical machines comprising a squarer for squaring a first quantity representative of the actual current; means for generating a second quantity representative of the square of a rated current for the machine; a subtractor connected to the squarer and the generating means and operative to subtract said second quantity from said first quantity; and an integrator connected to the output from the subtractor for integrating such subtraction with respect to time, and which is connected to a display unit for indicating a measurement for the loading of the machine.
6. A device according to Claim 5 including a threshold value monitor also connected to the integrator for indicating when said measurement reaches a predetermined value.
7. A device according to Claim 6 wherein the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A method and overload safety device for the monitoring of the effective current in direct current electrical machines The invention relates to the monitoring of the effective current in direct current electrical machines to prevent overloading, and an electronic overload safety device therefor. The monitoring of the effective current in direct current electrical machines has to date been carried out if at all, in complicated electronic calculating circuits. This mode of operation was only capable of being carried out with costly equipment and installations. The setting of these installations was very time-consuming, since for the operation a series of initial data on the installation to be monitored has to be ascertained. The present invention seeks to prevent overloading of direct current electrical machines by monitoring of the effective current therein. By monitoring the effective current, the load of the drive can be established and the drive protected from overloading. According to the invention a method of monitoring the effective current in a direct current electrical machine comprises squaring a first quantity representative of the actual current; subtracting therefrom a second quantity representative of the rated current; and integrating the difference over time, the integration being indicated as a measurement for the loading of the machine. Normally, the first and second quantities are respectively the actual current and the square of the rated current. The integration can be used to control the load on the machine. An overload safety device according to the invention comprises a squarer for squaring a first quantity representative of the actual current; means for generating a second quantity representative of the square of a rated current for the machine; a subtractor connected to the squarer and the generating means and operative to subtract said second quantity from said first quantity; and an integrator connected to the output from the subtractor for integrating such subtraction with respect to time, and which is connected to a display unit for indicating a measurement for the loading of the machine. A threshold value monitor may be included, for indicating when said measurement reaches a predetermined value. According to the invention, starting from the rated current of the machine, there is a simple, uncomplicated monitoring with a very high information content for the operator of the installation. Further, the invention enables an effective security against overloading to be established. The invention will now be described by way of example and with reference to the accompanying drawing which shows a block diagram of a device embodying the invention. In the system illustrated, the actual current (1iso) is fed into a squarer 1, and is squared. Connected with the squarer 1 is a subtractor 3, in which the square of the rated current (12N) iS deducted from the square of the actual current (12,5t). The square of the rated current (12N) iS fed to the subtractor 3 from a constant voltage source 2. When a positive difference occurs (1215t12N > O) the difference is accumulated in an integrator 4 over time. The content of the integrator 4 is shown in the display 7. The value indicated there is a measurement for the time, which must be evaluated, until the monitored machine can be loaded again. At the same time the content of the integrator 4 is compared in an electronic threshold value monitor 5. With a value of < 0, the signal is given, by way of an optical or acoustic indicator, here a signal lamp 6, that the machine is ready to operate. With a value of > 0, the re-starting of the machine should not take place because of the risk of a thermal overload, until the value has become =O or < 0 after a pause. For this, an automatic reclose blocking can be provided. The operation of the circuit shown is also obtainable with modules of digital technology. Claims
1. A method of monitoring of the effective current in a direct current machine to prevent overloading, comprising squaring a first quantity representative of the actual current; subtracting therefrom a second quantity representative of the rated current; and integrating the difference over time, the integration being indicated as a measurement of the loading of the machine.
2. A method according to Claim 1 wherein the integration is used to control the load on the machine.
3. A method according to Claim 1 or Claim 2 wherein the first and second quantities are respectively the actual current and the square of the rated current.
4. A method of monitoring the effective current in a direct current electrical machine substantially as described herein with reference to the accompanying drawing.
5. An electronic overload safety device for direct current electrical machines comprising a squarer for squaring a first quantity representative of the actual current; means for generating a second quantity representative of the square of a rated current for the machine; a subtractor connected to the squarer and the generating means and operative to subtract said second quantity from said first quantity; and an integrator connected to the output from the subtractor for integrating such subtraction with respect to time, and which is connected to a display unit for indicating a measurement for the loading of the machine.
6. A device according to Claim 5 including a threshold value monitor also connected to the integrator for indicating when said measurement reaches a predetermined value.
7. A device according to Claim 6 wherein the threshold value monitor is equipped with an optical or acoustic indicating mechanism.
8. A device according to any of Claims 5 to 7 including means responsive to the display unit for controlling the operation of a said machine.
9. An electronic overload safety device for direct current electrical machines substantially as described herein with reference to the accompanying drawing.
GB08215134A 1981-05-25 1982-05-24 Overload monitor for electrical machines Expired GB2101430B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE3121779A DE3121779C2 (en) 1981-05-25 1981-05-25 Method for monitoring the effective current in DC machines to prevent overload and electronic overload protection for carrying out the method

Publications (2)

Publication Number Publication Date
GB2101430A true GB2101430A (en) 1983-01-12
GB2101430B GB2101430B (en) 1985-01-09

Family

ID=6133693

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08215134A Expired GB2101430B (en) 1981-05-25 1982-05-24 Overload monitor for electrical machines

Country Status (10)

Country Link
JP (1) JPS57199492A (en)
BE (1) BE893263A (en)
CS (1) CS233724B2 (en)
DD (1) DD202082A5 (en)
DE (1) DE3121779C2 (en)
ES (1) ES8303708A1 (en)
FR (1) FR2506535A1 (en)
GB (1) GB2101430B (en)
IT (1) IT1218315B (en)
RO (1) RO83801B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2141884A (en) * 1983-05-18 1985-01-03 R L & D Limited Electric water heaters
GB2154813A (en) * 1984-02-28 1985-09-11 Dolphin Showers Limited Electric water heaters
DE3914312A1 (en) * 1989-04-29 1990-10-31 Telefunken Electronic Gmbh Motor overload detection circuit for hand-tool - compares current and voltage values obtained from current flux angle and motor revs
WO2007020146A1 (en) * 2005-08-12 2007-02-22 Robert Bosch Gmbh Method and device for detecting an overload in hand tools
WO2020047194A1 (en) 2018-08-30 2020-03-05 Texas Instruments Incorporated Method and circuit for detecting motor winding over temperature

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007013551A1 (en) 2007-03-19 2008-09-25 Siemens Ag Method for automatically setting a protective device having an overcurrent release, in particular a low-voltage circuit breaker

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2630407A1 (en) * 1976-07-06 1978-01-12 Siemens Ag DEVICE FOR MONITORING THE HEATING OF A CURRENT ELECTRICAL DEVICE
JPS55157927A (en) * 1979-05-24 1980-12-09 Fuji Electric Co Ltd Electronic overload protecting device
DE2922197A1 (en) * 1979-05-31 1980-12-04 Hirschmann Radiotechnik AUTOMATIC OVERLOAD SHUTDOWN DEVICE FOR DC MOTOR DRIVES
US4291355A (en) * 1979-07-30 1981-09-22 General Electric Company Programmable overload circuit

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2141884A (en) * 1983-05-18 1985-01-03 R L & D Limited Electric water heaters
GB2154813A (en) * 1984-02-28 1985-09-11 Dolphin Showers Limited Electric water heaters
DE3914312A1 (en) * 1989-04-29 1990-10-31 Telefunken Electronic Gmbh Motor overload detection circuit for hand-tool - compares current and voltage values obtained from current flux angle and motor revs
WO2007020146A1 (en) * 2005-08-12 2007-02-22 Robert Bosch Gmbh Method and device for detecting an overload in hand tools
US8018182B2 (en) 2005-08-12 2011-09-13 Robert Bosch Gmbh Method and device for an overload detection in hand-guided power tools
WO2020047194A1 (en) 2018-08-30 2020-03-05 Texas Instruments Incorporated Method and circuit for detecting motor winding over temperature
EP3844511A4 (en) * 2018-08-30 2021-10-27 Texas Instruments Incorporated Method and circuit for detecting motor winding over temperature

Also Published As

Publication number Publication date
GB2101430B (en) 1985-01-09
DE3121779C2 (en) 1984-02-02
IT1218315B (en) 1990-04-12
DD202082A5 (en) 1983-08-24
ES510277A0 (en) 1983-02-01
JPS57199492A (en) 1982-12-07
IT8220165A0 (en) 1982-03-15
FR2506535A1 (en) 1982-11-26
BE893263A (en) 1982-09-16
RO83801B (en) 1984-04-30
RO83801A (en) 1984-04-02
CS233724B2 (en) 1985-03-14
DE3121779A1 (en) 1982-12-23
ES8303708A1 (en) 1983-02-01

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PCNP Patent ceased through non-payment of renewal fee