SU928512A1 - Device for overtemperature protection of electric motor - Google Patents

Description

(5) DEVICE FOR ELECTRIC MOTOR TEMPERATURE PROTECTION

one

The invention relates to electrical engineering and is intended to protect electrical consumers from overheating.

Known devices containing a trigger amplifier with a thermal sensor in the input circuit and an actuating element at the output l.

The disadvantage of the device is the complex design and lack of self-control over the circuit of the sensor.

The closest technical solution to the invention is a device comprising two chains connected to a power source, performed on a series-connected thyristor and an actuating element, and a thermal sensor and a resistor 2.

The disadvantage of the device is a complex design, lack of reliability and complexity of the MS: device on the object, as well as from the sensor to usability, you need to lay two wires.

The purpose of the invention is to simplify the device and increase the reliability of its operation.

The delivered hCel is achieved by the fact that, in the thyristor control transition device, through two entered counter-connected diodes is connected to the output of the voltage divider

Claims (2)

10 resistor and temperature sensor, and parallel to the first voltage divider, the third voltage divider is connected to the newly introduced first capacitor, the third diode and the potentiometer connected in series, the common point of the first capacitor and the third diode is connected through the fourth diode to the output of the second divider voltage However, 30 by the fact that the output of the second voltage divider is connected to the thyristor anode through a second newly introduced capacitor. 39 The drawing shows a diagram of the device. The device contains a thyristor 1, an actuating element 2, a resistor 3, a thermal sensor 4, diodes 5-8, capacitors 9 and 10, and potentiometer 11. The device operates as follows. In the initial state, the device is supplied with a supply voltage to It, the capacitor 9 is charged to the voltage determined by the voltage divider 3 and l, and the capacitor 10 to a voltage equal to the voltage on the capacitor 9. The thyristor 1 is closed, the executive element 2 is turned off. When a short-time control signal is applied to the Input of the device, the thyristor 1 opens, and the actuating element 2 connects the power consumer to the mains. In this case, the capacitor 10 is charged up to a voltage equal to the voltage on the tripodizer. In the next half-period of the supply voltage, the voltage of the power source Ec is zero. The capacitor 9 is discharged through the diode 8, the potentiometer 11, the thyristor 1 and the actuating element 2, keeping it in the on state. The voltage on the capacitor 10 is less than the voltage on the capacitor 9, therefore, during the discharge of the capacitor 9, the voltage on it in one half-cycle of the supply voltage remains all the time greater than the voltage on the capacitor 10. In this connection, the capacitor 10 does not have on the process of the device. In the next half-period of the supply voltage, the thyristor 1 and the actuating element 2 are held in the on state by the supply voltage. Simultaneously, the capacitor 9 is recharged. The charging of the capacitor 10 is performed. Due to this, at the initial moment of the supply voltage, the thyristor 1 maintains the charging current of the capacitor 10 in the open state. When an electrical overload occurs, the temperature of its elements increases. This leads to an increase in the resistance of the thermal sensor k. When the temperature of the power consumption elements exceeds the maximum permissible value for this class of insulation, the resistance of the thermal sensor increases and becomes 4 times the maximum value. The voltage on the capacitor 9 decreases and becomes insufficient to keep the thyristor 1 in the on state. Thyristor 1 is closed, the actuator 2 disconnects the electrical consumer from the mains. It is possible to re-enable the power consumer after the temperature of the power consumer components is below the maximum permissible value. In case of a sudden short circuit of the thermal sensor during operation of the power consumer, the capacitor 10 recharges and closes the thyristor 1. The actuating element 2 disconnects the power consumer from the mains. When the thermal sensor k breaks during the operation of the power consumer or at the initial moment of the power consumer start up after the discharge of the capacitor 9, the thyristor-1 is closed, and the actuating element 2 disconnects the power consumer from the mains. In the event of a short circuit of the thermal sensor circuit at the initial moment of the start of electric power The control signal from the Input does not go through the control transition of the thyristor 1, as it is shunted by a short-circuited thermal sensor. It is possible to re-enable the electrical consumer after the restoration of the thermal sensor circuit. Apparatus of the Invention A device for thermal protection of an electric motor comprising two voltage dividers connected to a power source, the first of which is made on a series-connected thyristor and an actuator, and the second on a thermal sensor and a resistor, in order to simplify the device and increase reliability his work, controlling the thyristor junction - through two entered counter-switched diodes is connected to the output of a voltage divider on a resistor and a thermal sensor, and parallel to the first case Tieliu voltage included the newly introduced third voltage divider configured to posledo- aatelno connected again extracted the first capacitor, the third diode and the potentiometer; the common point of the first capacitor and the third diode is connected via the newly introduced fourth diode to the output of the second voltage divider. 2. The device according to claim 1, about t l and so on, that the output of the second voltage divider is connected 9285126 with the anode of the thyristor through the second newly introduced capacitor.  Sources of information 5 taken into account in the examination 1. Author's certificate of the USSR .If A32631, cl. H 02 H 7/08, 1976. 2. USSR author's certificate “357644, cl. H 02 H 7/08, 1972.