JPS5943802Y2 - Rotor overheat protection device for rotating electric machines - Google Patents

Description

[Detailed Description of the Invention] This invention enables a signal to be obtained when the rotor temperature of a rotating electric machine reaches a certain value, thereby protecting the rotor from overheating.

Conventionally, a protective device that detects the temperature of the rotor and receives a signal when the temperature reaches a certain level has been used (for example, a search coil is embedded in the coil of the rotor, and the output electric signal is used as the axis of the slip protection device). There is one that is taken out to the outside through a ring, but the structure is complicated due to the provision of a slip ring, and the operation is unstable due to contact resistance with the brush, resulting in poor reliability.

Furthermore, in the case where the heat-sensitive element is provided at a fixed part near the rotor without using a slip ring, rapid temperature changes cannot be detected because the hot water temperature is measured indirectly through the air.

For this reason, in any case, when the protection device is activated by the detection signal, the protection circuit is activated early with a considerable margin in mind, and it is necessary to increase the heat resistance capacity of the rotor. It's in shape.

This proposal has been improved in view of these points. In the embodiment shown in the figure, 1 is the rotor, 2 is the rotating shaft, and 3 is the heat generating part of the rotor, such as embedded in the iron core or coil of the rotor. A heat-sensitive element attached directly to a thermostat, for example, has a contact that closes when the temperature rises to a predetermined temperature.
This contact is connected between a conductive part of the rotor, such as the rotor coil or commutator 4, and a part insulated from the conductive part, such as the rotating shaft 2, and a suitable current limiting resistor 5 is inserted into this connection circuit. It is.

Reference numeral 6 denotes an earth leakage detector connected to a fixed part of the rotating electric machine and installed in a control panel or the like.

When the temperature of the rotor 1 rises during operation and exceeds a permissible value, the thermostat 3 operates to close the contacts.

Therefore, a small current flows from the conductive part of the rotor 1 to the rotating shaft 2 via the current limiting resistor 5, causing a current leakage, which activates the leakage detection relay 6 to perform protection such as interrupting the main circuit.

In this way, the present invention provides a heat-sensitive element in the heat-generating part of the rotor that has a contact that closes when a predetermined allowable upper temperature limit is reached, and connects this contact between the conductive part of the rotor and the rotating shaft. A suitable current limiting resistor is inserted into the connecting circuit to be connected, and by closing the contacts, a slight current leakage is generated from the rotor conductive part to the fixed part via the rotating shaft, and this is detected by a leakage detector connected to the fixed part. Because of this, the temperature of the rotor can be directly detected using a heat-sensitive element, and it is detected electrically at a fixed part without the need for a sliding part such as a slip ring, making it possible to perform reliable detection with a simple structure. .

Therefore, there is no need to increase the heat resistance of the rotor more than necessary, the overall size is smaller, and the earth leakage detector can also be used in common with the one provided for normal earth leakage protection. be.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the present invention. 1 is a rotor, 2 is a rotating shaft, 3 is a heat-sensitive element, 4 is a commutator,
5 is a current limiting resistor, and 6 is a leakage detector.

Claims (1)

[Scope of utility model registration request] A rotor overheat protection device that detects when the rotor temperature of a rotating electrical machine has reached a certain value includes a heat-sensitive element that is attached to a heat-generating part of the rotor and has a contact that closes at the upper limit of an allowable temperature, and a heat-sensitive element that A connection circuit connected between the conductive part of the rotor and the rotating shaft, a current limiting resistor inserted in this connection circuit, and a heat-sensitive element connected to the rotating electrical machine fixing part actuate the conductive part of the rotor to the stator. A rotor overheat protection device for a rotating electrical machine, characterized by comprising an earth leakage detector that detects a flowing minute earth leakage current.