JPS6353783B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention directly detects the temperature of the rotor winding of a rotating electric machine and detects overheating of the rotor winding to protect the rotor winding from overheating. It is related to the device.

[Conventional technology]

Conventionally, the overheat protection method for the rotor winding has been to use an overcurrent relay to protect against overheating of the winding. The rotor windings were protected by wind pressure relays, or by embedding temperature sensing elements in the fixed windings to detect and protect the rotor windings from temperature increases.

[Problem that the invention seeks to solve]

However, in a rotating electric machine, there is generally a difference in temperature rise characteristics between the rotor winding and the fixed part winding, and therefore, the protection against overheating of the rotor winding is indirect and incomplete.

[Means to solve the problem]

This invention was made with attention to the above-mentioned points, and includes a temperature sensing element embedded in the rotor winding of a rotating electrical machine, and a series-connected circuit such as a DC relay operated by the temperature sensing element. Equipped with
The present invention has realized a device that can be widely used in various rotating electric machines that obtains overheat protection signals from the series-connected circuits.

[Effect]

With this means, it is possible to directly monitor the temperature rise of the rotor windings, and the reliability of the rotating electric machine can be improved.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 to 6.

Figure 1 is a schematic connection diagram of a rotor-fed three-phase shunt commutator motor. Power is supplied from an AC power supply (not shown) to the rotor primary winding 3 through the primary lead wire 1 and the slip ring 2, and the motor is operated. be done. A temperature sensing element 4 that closes only when the temperature of the primary winding 3 is higher than the permissible temperature of the winding.
is embedded, and one terminal thereof is connected to one piece 6a of a commutator 6 connected to the adjustment winding 5. The other terminal is grounded to the rotor structure portion 7. On the other hand, one terminal 10 of the stator secondary winding 9 connected to the brush 8 is connected to a current limiting resistor 11, a rectifying element 12, and a DC relay 13.
Connect the coils in series and ground the ends. The rectifying element 14 uses a Zener diode, and the relay 13
This is to suppress the voltage applied to the coil of the relay 13 and to form a discharge current path for the coil of the relay 13. Resistor 11, rectifier 12, relay 13
In the general case where there is no , is insulated and floating. Connect resistor 1 to 1 terminal 10 in the secondary circuit.
1. By connecting the coils of the rectifying element 12 and DC relay 13 in series and grounding them, a weak current is caused to flow as if corresponding to the capacitance, and the coils of the secondary circuit 1
The ground voltage of the terminal 10 is potential-fixed at a very small voltage.

In a normal state where the rotor primary winding 3 is at or below the allowable temperature, the temperature sensing element 4 is open, so no relay 1 is activated.
Coil 3 never operates. If the rotor primary winding 3 exceeds the permissible winding temperature during operation due to an overload or a drop in cooling air volume, etc., the temperature sensing element 4 closes, and current flows through the coil of the relay 13 to detect this. I can do it.

FIG. 2 is a diagram showing the principle of operation. To explain the operation, when the rotor primary winding exceeds the allowable temperature and the temperature sensing element 4 is closed, the voltage induced in the adjustment winding 5 is transferred to the commutator piece 6a and the brush 8. As the voltage between resistor 1
1, a current i flows across a series circuit of a rectifying element 12 and a coil of a relay 13, and energizes the relay 13. The voltage applied to both ends is a slip frequency voltage because it is a rotor-fed type, and as the commutator 6 rotates, it changes to maximum voltage a-c, intermediate voltage a-b, zero voltage a-a, and is proportional to the rotation speed. Since there is a cycle fluctuation, the voltage becomes a pulsating voltage with both frequencies superimposed, and the current i also becomes a pulsating flow. Although rectification is performed by the rectifying element 12, the DC relay 13 repeats energization and deenergization near the synchronous speed. In order to make this operation stable, an auxiliary relay 15 is provided, and the relay 13
The moment the energized contact 13a closes, the auxiliary relay 15 is energized, and the rotor primary winding is overheated by other contacts (not shown) of the auxiliary relay 15. It outputs a stable signal and drives an alarm circuit (not shown).
This protects against overheating by disconnecting the power supply and stopping the motor.

The resistor 11 is a current limiting resistor for passing a current suitable for the DC relay 13. Further, the line between d and e is connected to an arbitrary control power source, and the push button 16 is a push button for resetting the motor after it has stopped.

FIG. 3 is a schematic connection diagram of an embodiment of a stator-fed commutator motor. In FIG. 3, there is a stator winding which is not shown, and only the rotor is shown in this figure. A temperature sensing element 1 is attached to the rotor winding 17 connected to the commutator 19.
8, and connect one end of its terminal to 1 of commutator 19.
Connect to piece 19a. The other end is grounded to the rotor structure portion 20. On the other hand, an external secondary fixed circuit 22 connected to the brush 21 includes a current limiting resistor 23,
The rectifying element 24 and the coil of the DC relay 25 are connected in series, and their ends are grounded. A rectifying element 26 connected in parallel to the DC relay 25 uses a Zener diode to suppress the voltage applied to the coil of the relay 25 and to form a cosill discharge current path of the relay 25. The operating principle is to protect the rotor winding from overheating in the same way as shown in Figure 2 above.
The only difference in the operating current in the case of the stator-fed type is that the power supply frequency is superimposed on the cycle pulsation proportional to the rotational speed.

FIG. 4 is a schematic connection diagram of an embodiment for overheat protection of the rotor winding of a three-phase wound induction motor. There is a three-phase stator winding (not shown) in FIG. 4, and only the rotor 7 is shown in this figure. A three-phase secondary rotor winding 28 is wound around the rotor 27, and the three-phase lead wires are connected to a slip ring 29 and drawn out to the outside through a slip ring brush 33. Connected to the device or short circuit ring. A temperature sensing element 30 is embedded in the rotor winding 28, and one end of its terminal is connected to an arbitrary one connected to the slip ring 29.
It is connected to the lead wire 31 of the phase, and the other terminal is grounded to the structural part 32 of the rotor. On the other hand, a current limiting resistor 35, a rectifying element 36, and a coil of a DC relay 37 are connected in series to an external fixed circuit 34 of one phase different from the phase to which the temperature sensing element 30 is connected, and the ends thereof are grounded.
The rectifying element 38 connected in parallel to the coil of the DC relay 37 uses a Zener diode.
This is to suppress the voltage applied to the coil of the relay 37 and to form a discharge current path for the coil of the relay 37. The principle of operation is to protect the secondary rotor winding from overheating in the same manner as in FIG. Generally, the slip of a three-phase induction motor during normal full-load operation is a few percent, and the slip voltage is low, so it is necessary to select the resistor 35 and DC relay 37 that match the voltage.

FIG. 5 is a schematic connection diagram of an embodiment of a method for overheating protection of an armature winding of a DC machine whose power source is not grounded.
There is a field winding and a commutator winding which are not shown in this figure, and only the armature is illustrated in this figure.

A temperature sensing element 40 is embedded in the armature winding 39 connected to the commutator 41, and one end of its terminal is connected to the commutator 41.
41a, and the other end is grounded to the rotor structure portion 42. On the other hand, a current limiting resistor 4 is connected to an external fixed circuit 45 connected to the negative electrode brush 43.
6. Connect the coils of the DC relay 47 in series and ground the ends. A brush 44 indicates a positive electrode brush, and a rectifying element 48 connected in parallel to the coil of the DC relay 47 uses a Zener diode to suppress the voltage applied to the coil of the relay 47 and forms a discharge current path for the coil of the relay 47. It is for the purpose of The operating principle is the same as that shown in FIG.
Provide overheat protection. In addition, since the armature voltage of a DC machine changes depending on the rotation speed in the case of voltage control, the resistor 46 and DC relay 47 must be selected so that the armature voltage operates at the lowest armature voltage under load within the rated speed range. .

FIG. 6 is a schematic connection diagram of an embodiment of a method for protecting a rotating field winding from overheating when a field power source is not grounded in a rotating field type synchronous machine with a slip ring. There is a stator armature winding that is not shown in this figure, and this figure only shows the rotor. The rotor 49 has a field winding 51 wound around a rotating magnetic pole iron core 50, the lead wire of which is connected to a slip ring 54, and a brush 5.
6 to an external field power source (not shown). A temperature sensing element 52 is embedded in the field winding 51, one terminal of which is connected to the positive electrode side 55 of the slip ring,
The other end is grounded to the rotor structure portion 53. On the other hand, a current limiting resistor 58 and a coil of a DC relay 59 are connected in series to the external field circuit 57 on the negative pole side, and their ends are grounded. A rectifying element 60 connected in parallel to the coil of the DC relay 59 uses a Zener diode to suppress the voltage applied to the coil of the relay 59 and to form a discharge current path for the coil of the relay 59. The operating principle is the second one mentioned above.
As shown in the figure, the operating current in this case is a stable DC current, but the resistor 58 and DC relay 59 must be selected to match the lowest field voltage in normal use.

Furthermore, like this embodiment, it can also be applied to a rotating armature type synchronous machine where the power source is not grounded. The schematic connection diagram is the same as that of the three-phase wound induction motor shown in FIG. 4, and the operation is the same, but the difference is that the operating current is an AC half-wave rectified current of the power supply frequency.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a device with a simple structure that is equipped with special means for directly detecting the temperature of the rotor windings and can be widely used in various types of rotating electrical applications.

[Brief explanation of drawings]

FIG. 1 is a schematic connection diagram of a rotor-fed three-phase shunt commutator motor showing an embodiment of the present invention, and FIG. 2 is a diagram showing its operating principle. FIG. 3 is a schematic connection diagram of a rotor of a stator-fed commutator motor showing another embodiment of the present invention. FIG. 4 is also a schematic connection diagram of a rotor of a three-phase wound induction motor showing another embodiment of the present invention. FIG. 5 is also a schematic connection diagram of the rotor of a DC machine in which the power supply is not grounded in another embodiment of the present invention. FIG. 6 is also a schematic connection diagram of the rotor in another embodiment of the present invention in which the field power source is not grounded in a rotating field type synchronous machine with a slip ring. 1...Primary lead wire, 2, 29...Slip ring, 3...Rotor primary winding, 4, 18, 30, 4
0, 52...Temperature sensing element that closes only at a temperature higher than the permissible temperature of the winding, 5...Adjustment winding, 6, 19, 41...
... Commutator, 6a... Commutator piece, 7, 20, 32,
42, 53... Rotor structure part, 8, 21, 3
3... Brush, 9... Stator secondary winding, 10...
1 terminal of secondary circuit, 11, 23, 35, 46, 5
8... Current limiting resistor, 12, 24, 36...
Rectifying element, 13, 25, 37, 47, 59...DC relay, 13a... Contact of relay 13, 14,
26, 38, 48, 60...Relay coil discharge current path forming rectifying element, 15...Auxiliary relay, 1
5a...Contact of auxiliary relay 15, 16...Push button switch.

Claims (1)

[Claims] 1. A temperature-sensitive element that closes only at a temperature higher than the permissible temperature of the winding is embedded in the rotor winding of a rotating electric machine that has a commutator or slip ring, and one terminal of this temperature-sensitive element is connected to an ungrounded rotor circuit. The coil of a DC relay with Zener diodes connected in parallel, the current limiting resistor, and the rectifier are connected in series. One end of the circuit is connected to the brushes of the commutator or slip ring, and the other end of the series-connected circuit is grounded, and when the rotor winding of the rotating electrical machine reaches a permissible temperature or higher, the temperature sensing element closes, and the A rotor winding overheat detection device that obtains an overheat detection signal by energizing the coil of a DC relay.