JPS6226386A - Liquid pump controller - Google Patents

Abstract

PURPOSE:To discriminate between normal and abnormal operations at low temperature starting thus to protect a motor by providing a temperature sensor then determining the allowable time corresponding with the overcurrent of motor on the basis of a monitoring level curve defined with correspondence to the temperature measurement and performing monitoring control of the duration of overcurrent. CONSTITUTION:Upon start of a motor 14a under the low oil temperature of an oil pump 14, the allowable time t1 is determined from the low temperature monitoring level theta1 on the basis of the relation between the overcurrent I and allowable time (t). At the same time, a comparator 10 will monitor the current level of motor 14a or the duration and upon exceeding over the allowable time, a signal is produced to stop the motor 14a through a switch 11. In order to inform the operating condition of oil pump 14 to the transformer 1, a motor 14a stop signal is fed to the transformer controller. Under high temperature, the oil temperature is transmitted from the temperature sensor 5 to a temperature transducer 7 and the comparator 10 thus to select the high temperature monitoring level curve theta2. Consequently, the motor 14a is protected from overcurrent while the stable operation is realized under a low temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ring oil pump that is attached to oil-immersed equipment such as an oil-immersed transformer and pumps oil between a transformer tank and a cooler. The present invention relates to a device for detecting an abnormality.

[Conventional technology]

Figure 3 shows, for example, "New Edition: Transformer Design and Construction Method" (wL Kishoin Publishing, supervised by Hisao Kimura, second edition, second printing published) 189.
140 is a diagram showing the entire conventional oil-fed air-cooled oil-immersed transformer shown on page 140. FIG. In the figure, (υ is an oil-filled, air-cooled transformer with an oil insulating oil inlet (1a) and outlet (1b) provided above and below the sides of the transformer tank, (
2) is the oil pipe connected to the inlet (1a) and the discharge port (1b), (3) is the cooler installed in the middle of the oil pipe (2), and (4) is the middle of the oil pipe (2). The oil pump is installed in series below the cooler (3) and is driven by an electric motor (4a). 4 opens and closes the power supply (6), and the electric motor (4
This is a switch equipped with an overcurrent relay for starting and stopping a).

Next, the operation will be explained. S! By closing the It source four circuits with the switch (7) and operating the electric motor (4a),
The oil of the transformer ill can be circulated to the cooler (3).

When the oil pump starts operating in such a circuit,
If the oil temperature is normal, the engine will start normally, but if the oil temperature is low, the overcurrent relay of the switch (7), which is the abnormality detector for the oil pump, may operate and prevent the engine from starting. .

[Problem that the invention seeks to solve]

Since the conventional transformer tυ is configured as above,
If you start the oil pump (4) in cold weather, the fluid resistance inside the transformer (transformer +1) and piping (22) will increase because the oil temperature in the transformer (υ) has also decreased and the viscosity of the oil has increased. big,
There is a problem that the starting torque at startup is larger than that at room temperature, and since it takes time to reach a constant speed even after startup, an abnormal signal may be output even though it is operating normally. Ta. Alternatively, if the sensitivity of the overcurrent relay of the start-up switch (7) at low temperatures is reduced and set, the start-up at low temperatures will be improved.
Due to the reduced sensitivity, failures in the oil pump (4) may not be detected, resulting in problems such as having a serious effect on the transformation voltage ('a Ll).

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a control device that can distinguish between normal operation and abnormal operation during low-temperature startup.

[Means for solving problems]

The liquid pump control device according to the present invention is provided with a temperature sensor to detect the liquid temperature, determines a monitoring level curve according to the measured temperature, determines an allowable time according to the overcurrent of the electric motor based on this curve, A control device is provided to monitor the overcurrent time of the motor.

[Effect]

The liquid pump control device of the present invention can distinguish between normal operation and abnormal operation at startup when the oil temperature is low.
This protects the electric motor of the liquid pump.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

The transformer +17, cooler (3), and power supply - are the same as in the conventional case. (G) is an oil pipe with a cooler (3) installed in the middle, and is connected to the inlet (1a) and outlet (1b) of the transformer (υ); It is an oil pump such as a whirlpool type installed on the lower side!! fn, and is driven by an electric motor (14a). (5) is a piping (
(7) is a temperature sensor such as a thermocouple installed on the suction side of the oil pump (4) in order to directly or indirectly measure the oil temperature; (7) is a temperature transducer that converts the output of the temperature sensor (15) into voltage; , (8) is a current sensor such as a transformer or shunt that measures the electric motor (14a) of the oil pump α◆, (9) is a current transducer that converts the output of this current sensor (8) into voltage, and is the output of the temperature transducer (7) and the current transducer (
9) A comparison circuit for inputting, comparing and monitoring the output, αV is a no-fuse with a trip coil arranged between the motor (14a) and the power source 4 to operate and stop the motor (14a). This is a switch such as a breaker, and is operated by the signal from comparison circuit 4. (6) is a control device consisting of a temperature transducer (η), a current sensor (8), a current transducer (9), and a comparison m M ua s - when the switch is closed; (7) is a liquid such as insulating oil.

Next, the operation of the present invention configured as described above will be explained. Figure 2 is a diagram showing the monitoring level curves for the current and allowable time determined by the oil temperature. For example, when the electric motor (14a) is started when the oil temperature is low, the electric motor (14a) From the relationship between overcurrent (I) and allowable time (1), the allowable time (
tl) is determined. At the same time, the electric motor (1
Monitor the time that is the current value of 4a) and determine the allowable time Ul)
If it exceeds the limit, a signal will be issued and the switch aη will turn on the electric motor (14
a) Stop. Further, in order to inform the transformer of the operating state of the oil pump α, a stop signal for the transformer control device (not shown) (the motor (14a)) is sent.

At high temperature 1, oil temperature information is transmitted from the temperature sensor (5) to the temperature transducer (7) and comparison circuit 4, and the high temperature monitoring level curve (θ2) in FIG. 2 is selected. Also electric & (14a) (7) current (12
) are current sensor (8), current transducer (9),
The current information is transmitted to the comparison circuit 4, and the current
The allowable time (tl) corresponding to -motivation (14
a) The time that is the overcurrent value is monitored and the allowable time (tl
), a signal is issued and the switch outputs an electric current jtll (1
4a) is stopped. Also, as in the case of the above-mentioned low temperature, a stop signal of the electric power @ (14a) is sent to the transformer control device.

As described above, the monitoring level curve according to the temperature is determined, the allowable time (1) is determined based on the current value (1) of the electric fi (14a), and the time when the ftvJ machine (14a) is over-reduced is determined as above. When the allowable time (1) is exceeded, a signal is issued and the motor (14
a), thereby protecting the electric motor (14a) from overflow and stabilizing the operation at low temperatures. A stop signal can also be sent to the transformer +1) to take protective measures for the transformer 1υ.

Although the above embodiment has been described using an oil-immersed transformer which is an oil circulation device, other oil reconnaissance devices may be used, or a conduit such as a pipeline may be used. Although the liquid is shown as insulating oil, other liquids whose viscosity changes with temperature changes may also be used.

The temperature sensor (5) was installed on the suction side of oil pump q4,
It may also be installed in other locations such as tanks.

〔Effect of the invention〕

As described above, according to the present invention, the temperature of the liquid is measured with a temperature sensor, a monitoring level curve is determined according to this temperature level, and an allowable time is determined from the monitoring level curve according to the overcurrent of the motor. By stopping the electric motor when the overcurrent period of the electric motor exceeds the permissible time, there is an effect of protecting the electric motor.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an oil-immersed transformer which is an embodiment of the present invention, Fig. 2 is a diagram showing a monitoring level curve based on one hour of current, and Fig. 8 is a diagram showing the configuration of a conventional oil-immersed transformer. FIG. In the figure, (υ is an oil-immersed transformer, (February is oil piping, (3 is
(4) is the oil pump, (6) is the temperature sensor,
(6) is the control tgI device, (7) is the temperature sensor, (8) is the temperature transducer, (9) is the current transducer, the head is the comparison circuit, the light is the switch (no fuse breaker with trip coil), ) is an oil pump, (to) is a pipe (oil piping), and (7) is a liquid (insulating oil). In addition, in the figures, the same reference numerals refer to the same or corresponding parts.

Claims (10)

[Claims] (1) A liquid pump driven by an electric motor to send liquid into the pipeline, a temperature sensor that measures the temperature of the liquid, a monitoring level curve determined according to the measured temperature level at startup, and an overcurrent of the electric motor A control device for a liquid pump, comprising: a control device that determines a permissible time based on the monitoring level curve, and stops the motor when an overcurrent in the motor flows for longer than the permissible time. (2) The liquid pump control device according to claim 1, wherein the temperature sensor is disposed on the liquid pump suction port side. (3) The liquid pump control device according to claim 1, wherein the temperature sensor is installed so as to be able to directly measure the temperature of the liquid. (4) The liquid pump control device according to claim 1, wherein the liquid pump is a whirlpool pump. (5) The liquid pump control device according to claim 1, wherein the liquid pump is used as an oil pump for circulating insulating oil of an oil-immersed transformer. (6) The liquid pump control device according to claim 5, wherein the temperature sensor is disposed at the lower part of the side wall of the tank of the transformer. (7) The liquid pump control device according to claim 1, wherein the temperature sensor is a thermocouple. (8) The control device corresponds to a current sensor that measures the motor current of the liquid pump, a current transducer that converts the output of this current sensor to voltage, a temperature transducer that converts the output of the temperature sensor to voltage, and the output of the above temperature transducer. determines a monitoring level curve, determines a permissible time from the monitoring level curve according to the output of the current transducer, and outputs a signal when the overcurrent in the motor exceeds the permissible time; 2. The liquid pump control device according to claim 1, further comprising a switch for stopping the liquid pump. (9) The liquid pump control device according to claim 8, wherein the switch is a no-fuse breaker with a trip coil. (10) Claim 8 in which the current sensor is a current transformer
A control device for a liquid pump as described in .