Series resistance starting device for a direct current oil pump

Abstract

This utility model discloses a series resistance starting device for a DC oil pump, including a power supply device, a control device, a resistor device, a cut-off device, and a heat dissipation device. The series resistance starting device provided by this utility model can meet the combination and switching of various resistor specifications. One device can meet the starting and testing of multiple DC oil pumps with different power, solving the problem that various resistor starting devices of different specifications are required to test oil pump motors with different power, and further reducing the time cost and equipment cost of testing.

Description

Technical Field

[0001] This utility model relates to the field of DC emergency equipment technology for power plants, and in particular to an intelligent starting device for a DC emergency oil pump for a steam turbine. Background Technology

[0002] The DC oil pump is an emergency backup device in the turbine lubrication system, also known as an emergency oil pump. Its core function is to provide emergency lubrication for turbine bearings, preventing equipment damage due to lubrication interruption. When the plant power supply is interrupted or the AC oil pump fails, the DC oil pump automatically and quickly starts, supplying lubricating oil to the bearings in a very short time to prevent the bearing bushes from burning out due to lack of oil and ensuring safe shutdown. As the last line of defense for the lubrication system, it provides minimum lubrication under extreme conditions of complete AC power failure, so ensuring the normal start-up of the DC oil pump is crucial.

[0003] Due to the important role of the DC oil pump, it needs to respond quickly when needed. However, the DC oil pump has a large torque, and the instantaneous current of the DC motor during startup can reach 10 to 20 times the rated current. This can cause a large impact on the power supply system, resulting in power tripping, and may even cause overload impact or damage to the armature winding and commutator, which will further affect the normal operation of the steam turbine.

[0004] Therefore, by increasing the total resistance of the armature circuit through series resistance, the current amplitude can be effectively reduced, avoiding overload impact or damage to the power supply system, armature winding and commutator. The addition of resistance can reduce the initial electromagnetic torque and avoid mechanical impact; at the same time, it provides controllable torque output, making the motor acceleration process smoother and avoiding sudden speed changes that could cause oil supply circuit failure.

[0005] To ensure the normal operation of DC oil pumps, manufacturers conduct various performance tests on the pumps before delivery, including starting current, starting time, speed arrival time, and outlet pressure. The test conditions and operating conditions must be consistent with the actual usage site. Because they need to be matched with steam turbines of various power ratings, DC oil pumps also come in various power ratings, commonly ranging from 5.5kW to 75kW. Therefore, each DC oil pump requires different series resistor starting devices for testing. Different power DC motors have different armature windings, requiring matching starting resistors of different resistance values ​​to meet starting requirements. This necessitates the manufacturer configuring a large number of starting devices to meet testing needs and requires sufficient space to house multiple devices, resulting in high equipment costs, low testing efficiency, and large space requirements, directly increasing equipment and management costs.

[0006] To solve the above problems, an adjustable resistance starting device is needed to meet the testing requirements of DC oil pumps with different power ratings, thus avoiding increased costs and cumbersome operations caused by multiple devices. Summary of the Invention

[0007] To address the aforementioned technical problems, the purpose of this utility model is to provide a series resistor starting device for a DC oil pump, which solves the problem of multi-power adaptation through modular resistor combination and intelligent control.

[0008] The objective of this utility model is achieved through the following technical solution:

[0009] A series resistor starting device for a DC oil pump includes a power supply unit, a control unit, a resistor unit, a cut-off unit, and a heat dissipation unit integrated in the same cabinet.

[0010] The power supply device includes a 220V incoming circuit breaker and a DC220V / DC24V switching power supply;

[0011] The control device includes an HMI (human-machine interface), a programmable controller, and control software for a preloaded resistor combination control algorithm;

[0012] The resistor device is composed of five independent precision stainless steel resistors R1 to R5, and each resistor is encapsulated in a highly protective metal shell.

[0013] The cutting device includes five DC dedicated contactors and high-temperature resistant connecting cables, with each contactor connected in parallel with resistors R1 to R5 respectively;

[0014] The heat dissipation device includes a temperature sensor mounted on the resistor housing and an axial flow cooling fan;

[0015] The programmable controller controls the on / off state of contactors KM1 to KM5 through the DO output terminal, thereby realizing the series-parallel topology switching of the five sets of resistors.

[0016] Furthermore, in the control device, the HMI (Human Machine Interface) is connected to the programmable controller via an Ethernet port using the TCP / IP protocol.

[0017] Furthermore, the resistance values ​​of resistors R1 to R5 are configured in a geometric series, with a tolerance range of 1.5 to 2.2.

[0018] Furthermore, the control circuit uses a DC24V safe voltage, and the output of the switching power supply is equipped with an overcurrent protection module.

[0019] Furthermore, the temperature sensor of the heat dissipation device monitors the resistor temperature in real time and activates the axial flow cooling fan.

[0020] Furthermore, the axial flow cooling fan has a dust filter at the air inlet and heat dissipation fins facing the resistor device at the air outlet.

[0021] Furthermore, resistor combinations include all combinations from single resistors to five resistors in parallel.

[0022] Compared with the prior art, one or more embodiments of this utility model may have the following advantages:

[0023] One starting device can test multiple DC oil pumps of different power. The test power range is large, covering DC oil pump motors with power from 5.5KW to 75KW. Different resistance combinations can be adjusted through the HMI human-machine interface, programmable controller and control software, and DC oil pump motors of different power can be freely switched and matched, which facilitates the testing process and greatly shortens the testing time.

[0024] The heat dissipation system, consisting of a temperature sensor and a cooling fan, can reduce the temperature of the resistor in a timely manner, avoiding the situation where the resistor heats up due to frequent startups, thus affecting the accuracy of the resistance value. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the resistor circuit and cut-off circuit structure of the starting device of a DC oil pump;

[0026] Figure 2 This is a schematic diagram of the human-machine interface for the starting device of a DC oil pump.

[0027] Figure 3 This is a schematic diagram of the integrated control system for the starting device of a DC oil pump. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0029] Figures 1-3 The image shows the starting device for a DC oil pump, which includes a power supply unit, a control unit, a resistor unit, a cut-off unit, and a heat dissipation unit integrated in the same cabinet.

[0030] The power supply device includes a 220V incoming circuit breaker and a DC220V / DC24V switching power supply;

[0031] The control device includes an HMI (human-machine interface), a programmable controller, and control software for a preloaded resistor combination control algorithm;

[0032] The resistor device is composed of five independent precision stainless steel resistors R1 to R5, and each resistor is encapsulated in a highly protective metal shell.

[0033] The cutting device includes five DC dedicated contactors and high-temperature resistant connecting cables, with each contactor connected in parallel with resistors R1 to R5 respectively;

[0034] The heat dissipation device includes a temperature sensor mounted on the resistor housing and an axial flow cooling fan;

[0035] The programmable controller controls the switching of DC contactors KM1 to KM5 through the DO output terminal, thereby realizing the series-parallel topology switching of the five sets of resistors.

[0036] The power supply unit, control unit, resistor unit, and cut-off unit are used in conjunction with the heat dissipation unit. In the control unit, the HMI (Human Machine Interface) is connected to the programmable controller via an Ethernet port using the TCP / IP protocol. The HMI can intuitively display the resistance values ​​and operating status of each resistor combination. The control unit, cut-off unit, and heat dissipation unit are all powered by the power supply unit, which provides DC 24V.

[0037] The resistor device consists of five resistors with different resistance values, named R1, R2, R3, R4, and R5, and five DC contactors connected in parallel with the five resistance values. The resistance values ​​of R1 to R5 are arranged in a geometric series with a tolerance range of 1.5 to 2.2. Figure 1 As shown, they are named KM1, KM2, KM3, KM4, and KM5. The on / off state of KM1 to KM5 can be controlled by the programmable DO output, which can realize the individual use and combined use of R1 to R5.

[0038] 1. Use resistor R1 alone;

[0039] 2. Use resistor R2 alone;

[0040] 3. Use resistor R3 alone;

[0041] 4. Use resistor R4 alone;

[0042] 5. Use resistor R5 alone;

[0043] 6. Use resistors R1 and R2 together;

[0044] 7. Use resistors R1 and R3 together;

[0045] 8. Use resistors R1 and R4 together;

[0046] 9. Use resistors R1 and R5 together;

[0047] 10. Use resistors R2 and R3 together;

[0048] 11. Use resistors R2 and R4 together;

[0049] 12. Use resistors R2 and R5 together;

[0050] 13. Use resistors R3 and R4 together;

[0051] 14. Use resistors R3 and R5 together;

[0052] 15. Use resistors R4 and R5 together;

[0053] 16. Use resistors R1+R2+R3 in combination;

[0054] 17. Use resistors R1+R2+R4 in combination;

[0055] 18. Use resistors R1+R2+R5 in combination;

[0056] 19. Use resistors R1+R3+R4 in combination;

[0057] 20. Use resistors R1+R3+R5 in combination;

[0058] 21. Use resistors R1+R4+R5 in combination;

[0059] 22. Use resistors R2+R3+R4 in combination;

[0060] 23. Use a combination of resistors R2, R3, and R5;

[0061] 24. Use a combination of resistors R2, R4, and R5;

[0062] 25. Use a combination of resistors R3, R4, and R5;

[0063] 26. Use resistors R1+R2+R3+R4 in combination;

[0064] 27. Use a combination of resistors R1+R2+R3+R5;

[0065] 28. Use resistors R1+R2+R4+R5 in combination;

[0066] 29. Use resistors R1+R3+R4+R5 in combination;

[0067] 30. Use a combination of resistors R2+R3+R4+R5;

[0068] 31. Use resistors R1+R2+R3+R4+R5 in combination;

[0069] Based on the above permutations and combinations, up to 31 different resistance values ​​can be achieved, which can fully cover the resistance value requirements of starting resistors for all DC oil pump motors in the power range of 5.5KW to 75KW.

[0070] The control circuit uses a safe DC 24V voltage, and the output of the switching power supply is equipped with an overcurrent protection module. The temperature sensor of the heat dissipation device monitors the resistor temperature in real time and activates the axial cooling fan.

[0071] The axial-flow cooling fan has a dust filter at its air inlet and heat dissipation fins facing the resistor device at its air outlet. The resistor combination includes all combinations from a single resistor to five resistors connected in parallel.

[0072] During use, input the power of the oil pump to be tested (e.g., 30KW) into the HMI interface, and the control software will automatically match the R2+R3+R5 combination; the programmable controller outputs a DO signal to close contactors KM1 and KM4 and open KM2, KM3, and KM5; when the temperature controller detects that the casing of the resistor reaches 60℃, the control software starts the cooling fan to 2000rpm; an alarm is triggered at 70℃, and when the current exceeds the threshold, the overcurrent protection module cuts off the output of the switching power supply.

[0073] Calculating the starting resistance of oil pumps with different power ratings is a complex process. It requires substituting parameters such as rated current, number of starting stages, armature resistance, rated speed, and moment of inertia into a formula. For ordinary operators, the complex mathematical calculations are quite difficult. The control software of the device is pre-installed with the algorithm formula. You only need to input the corresponding power to automatically calculate the required resistance value, which saves tedious steps and improves the efficiency of testing.

[0074] Although the embodiments disclosed in this utility model are as described above, the content described is merely for the purpose of facilitating understanding of this utility model and is not intended to limit this utility model. Any person skilled in the art to which this utility model pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this utility model, but the patent protection scope of this utility model shall still be determined by the scope defined in the appended claims.

Claims

1. A series resistance starting device for a DC oil pump, characterized by comprising: This includes power supply units, control units, resistor units, cut-off units, and heat dissipation units integrated in the same cabinet; The power supply device includes a 220V incoming circuit breaker and a DC220V / DC24V switching power supply; The control device includes an HMI (human-machine interface), a programmable controller, and control software for a preloaded resistor combination control algorithm; The resistor device is composed of five independent precision stainless steel resistors R1 to R5, and each resistor is encapsulated in a highly protective metal shell. The cutting device includes five DC dedicated contactors and high-temperature resistant connecting cables, with each contactor connected in parallel with resistors R1 to R5 respectively; The heat dissipation device includes a temperature sensor mounted on the resistor housing and an axial flow cooling fan; The programmable controller controls the on / off state of contactors KM1 to KM5 through the DO output terminal, thereby realizing the series-parallel topology switching of the five sets of resistors.

2. The series resistance starting arrangement for a DC oil pump according to claim 1, characterized in that, In the control device, the HMI (Human Machine Interface) is connected to the programmable controller via an Ethernet port using the TCP / IP protocol.

3. The series resistance starting device for a DC oil pump according to claim 1, characterized in that, The resistance values ​​of resistors R1 to R5 are configured in a geometric series, with a tolerance range of 1.5 to 2.

2.

4. The series resistance starting device for a DC oil pump according to claim 1, characterized in that, The control circuit uses a safe DC24V voltage, and the output of the switching power supply is equipped with an overcurrent protection module.

5. The series resistance starting device for a DC oil pump according to claim 1, characterized in that, The temperature sensor of the heat dissipation device monitors the resistor temperature in real time and activates the axial flow cooling fan.

6. The series resistor starting device for a DC oil pump according to claim 1, characterized in that, The axial flow cooling fan has a dust filter at its air inlet and heat dissipation fins facing the resistor device at its air outlet.

7. The series resistance starting device for a DC oil pump as described in claim 1, characterized in that, The resistor combinations include all combinations from a single resistor to five resistors connected in parallel.

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