Arrangement for overload protection and method for reducing the current consumption in the event of mains voltage fluctuations

• US 20050162787A1
• Filed: 12/02/2004
• Published: 07/28/2005
• Est. Priority Date: 12/02/2003
• Status: Active Grant

• Current Assignee: Roland Weigel
• Original Assignee: Roland Weigel
• Inventors: Weigel, Roland
• Granted Patent: US 7,276,870 B2
• Time in Patent Office: Days
• US Class Current: 361/22
• CPC Class Codes: F04B 2203/0202 Voltage
• CPC Class Codes: F04B 49/10 Other safety measures
• CPC Class Codes: F04B 49/24 Bypassing
• CPC Class Codes: H02H 7/0857 by lowering the mechanical load of the motor

Abstract

The arrangement as overload protection for the mains voltage (U) comprises an electric motor (1), a compression unit having a compressor (2), a mains voltage-monitoring unit (3), a device for reducing the load on the motor (1) and a control arrangement (4). The control arrangement (4) is connected to the mains voltage-monitoring unit (3) and to the device for reducing the load on the motor (1) such that the motor (1) is disconnected from the load as soon as the mains voltage (U) falls below a predetermined, first threshold value. The load on the motor (1) comes from the pressure difference between the inlet (E) and the outlet (A) of the compressor (2), which is driven by the motor (1).

Claims

1-22. -22. (canceled)

23. Arrangement for overload protection of an electric motor of a compression unit having a compressor, the arrangement having

a mains voltage-monitoring unit,

a device for reducing the load on the motor and

a control arrangement which is connected to the device for the purpose of reducing the load in the event of the mains voltage falling below a predetermined, first threshold value.

24. Arrangement according to claim 23, further comprising at least one pressure-compensating valve on a bypass between the inlet and the outlet of the compressor for reducing the pressure between the pressure at the inlet and the pressure at the outlet.

25. Arrangement according to claim 23, wherein the connection the electric motor to the compressor is made via a coupling such that it can be adjusted and/or disconnected.

26. Arrangement according to claim 23, wherein the mains voltage-monitoring unit has a voltage comparator.

27. Arrangement according to claim 23, wherein the control arrangement is in interacting connection with a device for switching the electric motor off, such that the electric motor is switched off when the undervoltage lasts longer than a predetermined period of time.

28. Arrangement according to claim 23, wherein the electric motor is provided with a device for reducing current consumption during start-up.

29. Arrangement according to claim 28, wherein the device for reducing the current consumption during start-up of the electric motor comprises

an NTC thermistor which can be connected in series with a main winding, and

an arrangement, which can be connected in series with an auxiliary winding, comprising an NTC thermistor and a start-up capacitor.

30. Arrangement according to claim 23, wherein the control arrangement is in interacting connection with a device for switching the electric motor on, such that the electric motor is only switched on when the mains voltage rises above a second threshold value.

31. Arrangement according to claim 23, wherein the control arrangement is in interacting connection with a device for connecting the electric motor to the load, the load only being connected to the electric motor when the motor has reached a predetermined speed.

32. Arrangement according to claim 23, wherein the compression unit is built into an air-conditioning system or a refrigerator.

33. Method for reducing the current consumption of an electric motor driving a compression unit in the event of mains voltage fluctuations, in particular in the event of a reduction in the mains voltage, comprising the steps of:

monitoring the mains voltage

reducing the load on the electric motor caused by the compressor when the mains voltage falls below a first threshold value, such that the electric motor is running at approximately no-load.

34. Method according to claim 33, wherein the load is removed from the electric motor by reducing the pressure difference between the pressure at the inlet and the pressure at the outlet of the compressor.

35. Method according to claim 33, wherein the pressure difference between the pressure at the inlet and the pressure at the outlet of the compressor is reduced to zero.

36. Method according to claim 34, wherein the pressure difference is reduced by opening and/or closing one or more valves in a bypass between the inlet and the outlet of the compressor.

37. Method according to claim 33, wherein the load is disconnected from the electric motor by means of a coupling.

38. Method according to claim 33, wherein the time during which the electric motor is at no-load is measured, and wherein the electric motor is switched off after a predetermined period of time at no-load.

39. Method according to claim 33, wherein the current through the electric motor is reduced during the start-up phase.

40. Method according to claim 39, wherein, during the start-up phase, an NTC thermistor is connected in series with a main winding, and an arrangement comprising a start-up capacitor in series with an NTC thermistor is connected in series with an auxiliary winding.

41. Method according to claim 33, wherein the electric motor is connected to the load of the compressor only once a predetermined speed has been reached.

42. Method according to claim 33, wherein the first threshold value for reducing the load on the electric motor is 80 to 90% of the rated voltage, preferably 85% of the rated voltage.

43. Method according to claim 33, wherein the second threshold value for increasing the load on the electric motor is 90 to 95% of the rated voltage.

44. Method according to claim 33, wherein the load on the electric motor is reduced within less than 30 ms, preferably within approximately 20 ms.