Motor starter and diagnosis method

Patent metadata

Field	Value
Publication number	US-10873279-B2
Application number	US-201716077820-A
Country	US
Kind code	B2
Filing date	Feb 3, 2017
Priority date	Mar 8, 2016
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

The invention relates to a motor starter (10) for an electric motor (20), wherein the motor starter (10) comprises a first and a second phase (12, 14). Said motor starter and electric motor each have an associated switching apparatus (29, 31) which each have an electromechanical switch (22, 24) and a semiconductor switch (23, 25) connected to form a bypass circuit. The electromechanical switches (22, 24) and the semiconductor switches (23, 25) are designed to be separately operable by a control unit (40), and the first and the second phase (12, 14) are connected to a passive overcurrent protection means (30). The passive overcurrent protection means (30) has a fuse (32, 34, 36) for each phase. According to the invention, a measuring apparatus (42, 44) is arranged in at least one of the phases (12, 14) along the phase direction directly between the passive overcurrent protection means (30) and at least one of the switching apparatuses (29, 31). The invention further relates to diagnosis methods (100, 200, 300) with which defects in the motor starter (10) can be diagnosed during an activation sequence.

First claim

The invention claimed is:

1. A motor starter for an electric motor, the motor starter comprising:
a first phase and a second phase;
the first phase and the second phase each comprising an associated switching apparatus, each associate switching apparatus comprising an electromechanical switch and a semiconductor switch connected to form a bypass circuit;
wherein the electromechanical switches and the semiconductor switches are configured to be separately operable by a control unit, wherein the first phase and the second phase are connected to a passive overcurrent protection device that comprises a first fuse for the first phase and a second fuse for the second phase; wherein a measuring apparatus is connected in at least one of the phases along a phase direction and positioned directly between the passive overcurrent protection device and at least one of the associated switching apparatuses.

2. The motor starter of claim 1 , at least one of the associated switching apparatuses includes a continuously operating current limit that corresponds to an intended operating current.

3. The motor starter of claim 1 , wherein at least one of the fuses a triggering duration at a reference current intensity corresponding to a reaction time of at least one of the associated switching apparatuses.

4. The motor starter of claim 3 , wherein at least one of the associated switching apparatuses is configured to withstand the reference current intensity for the reaction time.

5. The motor starter of claim 1 , wherein a first measuring apparatus is arranged in the first phase and a second measuring apparatus is arranged in the second phase.

6. The motor starter of claim 1 , wherein in the first phase and the second phase a reversible switching device for interchanging the first phase and the second phase is connected.

7. A diagnostic method for a motor starter configured as a direct starter and connected to a three-phase electric motor, the method comprising:
providing the motor starter in an inactive state;
closing of a first phase with a first electromechanical switch;
opening of the first phase and closing of a third electromechanical switch in a third phase;
closing of a first semiconductor switch in the first phase and a second semiconductor switch in a second phase by active control of the first and second semiconductor switches;
closing of a first electromechanical switch in the first phase and a second electromechanical switch in the second phase, wherein each of the first electromechanical switch and the second electromechanical switch form a bypass circuit with the first and second semiconductor switches;
rejecting active control of the first and second semiconductor switches;
wherein a fault in the motor starter detected when during closing of the first semiconductor switch in the first phase and closing of the second semiconductor switch in a second phase or opening of the first phase and closing of the third electromechanical switch in the third phase a current flow is detected by at least one measuring apparatus in the first phase, the second phase, or the first phase and second phase or when during closing of the first semiconductor switch in the first phase and closing of the second semiconductor switch in the second phase a current flow of zero is detected by-the at least one measuring apparatus in the first phase, the second phase, or the first phase and the second phase.

8. A diagnostic method for a motor starter configured as a reversing starter and connected to a three-phase electric motor, the method comprising:
providing the motor starter in an inactive state;
closing of a first semiconductor switch in a first phase and closing of a second semiconductor switch in a second phase;
opening of the first and the second semiconductor switch and closing of a reversible switching device or a direct switching device in the second and a third phase;
closing of the first and second semiconductor switch;
closing of a first electromechanical switch in the first phase and a second electromechanical switch in the second phase that each form a bypass circuit with the first and second semiconductor switches;
rejecting of active control of the semiconductor switches;
wherein a fault in the motor starter is detected when during closing or opening of the first semiconductor switch a current flow is detected by at least one measuring apparatus in the first phase, the second phase, or the first phase and the second phase or when during closing of the first and second semiconductor switches a current flow of zero is detected in the first phase, the second phase, or the first phase and the second phase by the at least one measuring apparatus.

9. The diagnostic method of claim 7 , wherein a defect in the first or second semiconductor switch is detected if during closing of the first semiconductor switch in the first phase and closing of the second semiconductor switch in the second phase a current flow of zero is detected, and closing of the first electromechanical switch in the first phase and closing of the second electromechanical switch in the second phase current flow is detected by the at least one measuring apparatus.

10. The diagnostic method of claim 7 , wherein a freedom of the electric motor from an electrical load is detected if a current flow of zero is detected by the at least one measuring apparatus during closing of the first semiconductor switch in the first phase and closing of the second semiconductor switch in the second phase and during closing of the first electromechanical switch in the first phase and closing of the second electromechanical switch in the second phase.

11. The diagnostic method of claim 7 , wherein a defect in the first or second electromechanical switch is detected if a current flow of zero is detected by the at least one measuring apparatus during rejecting of the active control of the first and second semiconductor switches.

12. A diagnostic method for a motor starter configured as a direct starter and connected to a single-phase electric motor, the method comprising:
providing the motor starter in an inactive state;
closing a first phase with a first electromechanical switch;
opening the first phase;
closing a first semiconductor switch in the first phase and a second semiconductor switch in a second phase by active control of the first and second semiconductor switches;
closing a first electromechanical switch in the first phase and a second electromechanical switch in the second phase that each form a bypass circuit with the first and second semiconductor switches;
rejecting the active control of the first and second semiconductor switches;
wherein a fault in the motor starter is detected if when closing the first phase a current flow is detected by at least one measuring apparatus in the first phase, second phase, or first and second phase when closing the first semiconductor switch in the first phase and the second semiconductor switch in the second phase a current flow of zero is detected by the at least one measuring apparatus in the first phase, second phase, or first and second phase.

13. The diagnostic method of claim 12 , wherein a defect in the first or second semiconductor switch is detected if a current flow of zero is detected when closing the first semiconductor switch in the first phase and the second semiconductor switch in the second phase and a current flow is detected by the at least one measuring apparatus when closing the first electromechanical switch in the first phase and the second electromechanical switch in the second phase.

14. The diagnostic method of claim 12 , where

Assignees

• Siemens Ag

Inventors

• Ahnert Karsten
• Almen Gernot-Dirk
• Fiedler Norbert
• Flor Bernd
• Nagy Franz
• Wohlrab Nico
• Wolf Albrecht

Classifications

• H02P1/023 Primary

  Protection against sparking of contacts or sticking together · CPC title

• H02H9/001

  limiting speed of change of electric quantities, e.g. soft switching on or off (progressive control of electronic switches for eliminating interferences H03K17/16) · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• H01H9/54

  Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere · CPC title

• H02P1/04

  Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter · CPC title