SU1319143A2 - Device for thermal protection of electric motor - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect motors. The purpose of the invention is to improve the accuracy of modeling the temperature of motor windings by taking into account its thermal state at the moment of increasing the load. If the temperature of the motor winding is different from the ambient temperature. then there is a residual voltage on the capacitor 1 1. If this voltage exceeds a certain limit value, the additional threshold unit 7 generates a pulse arriving at the information input of a clocked D-flip-flop 9. At the time the load increases, a pulse is generated at the output causing the switching of contacts 16 and 17. A further capacitor discharge occurs 11 to the resistor 14 and the charge of the capacitor 15. The executive unit 6 shuts off the engine in the event of the occurrence of signals from the threshold organs 4 ("when the permissible rate of increase of temperature is exceeded tours) or 5 (if the permissible overheating temperature of the windings is exceeded). The proposed device takes into account the initial conversion of the motor temperature over the ambient temperature of the 1st medium, which improves the accuracy of modeling the winding heating process. 2 Il. SS O) 00 SO tL. OO N: FIG.

Description

The invention relates to electrical engineering, can be used for thermal protection of electric motors and is an improvement of the device according to the author. St. No. 1089692.

The purpose of the invention is to improve the accuracy of modeling the winding temperature of an electric motor by taking into account its thermal state at the moment of increasing the load.

FIG. 1 shows a diagram of the device; in fig. 2 - simulated heating curves.

The device contains a current sensor 1, a quad 2, a thermal analog block 3, a first threshold organ 4, a second threshold organ 5, an actuator block 6, an additional threshold organ 7, a key element 8, and a clocked) trigger 9. The thermal analog block 3 consists of the first resistor 10 and the first capacitor 11, the second resistor 12 and the second capacitor 13, additional third resistor 14 and the third capacitor 15, two switching contacts 16 and 17.

A voltage proportional to the heat loss of the machine is supplied to the input of the thermal analog unit 3, and a voltage is removed from the output that is proportional to the temperature of the motor windings. The executive unit 6 shuts off the engine in case of occurrence of signals from threshold organs 4 (when the permissible rate of increase of temperature is exceeded) or 5 (when the permissible superheat temperature of the windings is exceeded).

In the initial state, the switching contacts 16 and 17 are in the position indicated in the diagram (Fig. I). When the engine is fully cooled, the device is charged with a capacitor 1 1 (Fig. 2, curve a).

If the temperature of the motor winding is different, this is the ambient temperature, then there is a residual voltage on the capacitor 1. If this voltage exceeds a certain value of UH, at which the initial heating is taken into account, an additional threshold organ 7 generates an impulse arriving at the information input of the tact

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D-flip-flop 9. At the time of increasing load, i.e., if there is a pulse at the clock input of a clocked D-flip-flop 9, a pulse is generated at its output, causing the switching of pins 16 and 17. In the future, a discharge of capacitor 1 is observed in the device 1 to the resistor 14 and the charge on the capacitor 15 (Fig. 2, curve b). The proposed thermal model allows to take into account the initial temperature of the electric motor over the ambient temperature, which improves the accuracy of modeling the heating process of the winding and eliminates the possibility of incorrect actions of the overheating protection device.

Claims (1)

Invention Formula Device for thermal protection of elec- tricles by aut. St. No. 1089692, characterized in that, in order to increase the accuracy of modeling the winding temperature of an electric motor by taking into account its thermal state at the moment of increasing the load, a third threshold organ, a key element, a clocked D-trigger, and a third capacitor connected between the first output are additionally introduced into it the first capacitor and the first resistor and shunted by the break contact of the newly introduced first switching element, the closing contact of which is connected to the newly introduced third resistor, the second the water of which is connected to the second output of the first capacitor, and through the disconnecting contact of the newly introduced second switching element to the connection point of the second capacitor and the second resistor, the closing contact of the second switching element is connected to the connection point of the first and third capacitor; the key element is connected to the current sensor output, and the output is connected to the clock input of a clocked D-flip-flop, the information input of which is connected to the output of the third threshold organ whose input is connected to 15Y THROUGH thermal analysis block. F1. yy |;.; o1: tavitel O. Muratov Tehred I. IJepee Corrector Jl. Nilipenko Ti |) already 618Subscription F-illllHIlH State Committee on Government, (, G.R. for do.and AM inventions 1,13035. okay F-ZG), 1 a) Nyuka nab., 4; 5 11ron.chvodst1km1no-nol11grafnical enterprise, Uzhgorod, st. Project PpjiaKTop N. Dumbass Order 2521/49