Dual pump motor starting device for propeller with distance control

Abstract

The application discloses a kind of dual pump motor starting device of distance adjusting oar mutual standby, main power circuit includes total power switch, contactor KM1, KM2, 1# and 2# pump motor etc.;Control circuit includes transformer, 1# and 2# pump motor starting button, reset button, time relay KT, relay K1 and K2.;The normally open contact of 1# pump motor starting button is connected in parallel with the first auxiliary normally open contact of contactor KM1, then the first auxiliary normally closed contact of contactor KM2 is connected in series, and then connected to the coil of contactor KM, to form the starting self-locking and interlocking circuit of 1# pump motor.;The normally open contact of 2# pump motor starting button is connected in parallel with the first auxiliary normally open contact of contactor KM2, then the first auxiliary normally closed contact of contactor KM1 is connected in series, and then connected to the coil of contactor KM2, to form the starting self-locking and interlocking circuit of 2# pump motor. The device can not only realize the various functions of redundant control of dual pump motor mutual standby.

Description

Technical Field

[0001] This invention relates to electrical control devices for ship controllable pitch propellers, and in particular to a dual-pump motor starting device that serves as a backup for each other. Background Technology

[0002] There are numerous types of devices for controlling the starting of pitch propeller pump motors both domestically and internationally. To ensure system reliability, many employ dual-pump motor redundant starting control, where one motor is fixed as the primary control motor and the other as a backup control motor via a knob. These pump motor control devices, designed to achieve dual-pump motor redundancy, have very complex circuits and involve numerous electrical control components, resulting in a high failure rate and increased maintenance difficulty. In recent years, devices using PLCs as the core controller for dual-pump redundant starting control have emerged, but their high cost has limited their widespread adoption.

[0003] In the prior art, for example, Chinese patent application publication number CN117231485A discloses a "Converter Tilting Thin Oil Lubrication Pump Master-Slave Automatic Control System". This system controls the switching between the master and slave pumps through the cooperation of intermediate relays, contactors, thermal relays, and pressure relays. Its basic logic is: the on / off signal of the pressure relay serves as the signal for switching the pump. When the master pump is running alone and the pressure is lower than a preset value, the pressure relay disconnects, the master pump motor stops, and the standby pump starts simultaneously. However, in practical applications, the aforementioned prior art (CN117231485A) has the following technical problems, affecting the system's stability and safety: it lacks a pressure signal delay confirmation mechanism and does not include a time delay element to filter transient pressure fluctuations; it lacks a fault self-locking and anti-oscillation mechanism and does not explicitly set a "lock-in after switching" mechanism, meaning that after switching, unless manually intervened, it should not automatically switch back to the original faulty pump or repeatedly switch between the two pumps. This may cause the two pumps to "oscillate" during switching in a faulty state, exacerbating equipment damage.

[0004] Therefore, there is an urgent need for a dual-pump motor starting device for controllable pitch propellers, in which two motors act as backups for each other. When either pump motor starts, it becomes the primary working pump, while the other pump motor remains in a standby, idle state. If the operating pump system malfunctions, causing low pressure in the hydraulic supply system, the standby pump starts, automatically entering working mode and stopping the motor of the malfunctioning pump, ensuring the reliable and normal operation of the hydraulic power source. Summary of the Invention

[0005] The technical problem to be solved by this invention is to design a dual-pump motor redundant control system to ensure the reliability of the hydraulic drive oil supply system of the controllable pitch propeller. At the same time, in order to reduce the equipment failure rate and reduce the difficulty of maintenance, this invention proposes a dual-pump motor starting device for mutual backup of controllable pitch propellers. It only requires three relays (two general-purpose relays and one time relay) to realize the various complex functions of the dual-pump motor redundant control of controllable pitch propellers. The device has a simple and clear design, uses few electronic components, has good maintainability, and high reliability.

[0006] To achieve the above objectives, the technical solution of the present invention is: a dual-pump motor starting device with a pitch control propeller as backup for each other, comprising a main power supply circuit and a control circuit; the main power supply circuit includes a main power switch, a #1 pump motor switch, a #2 pump motor switch, contactors KM1 and KM2, a #1 pump motor, and a #2 pump motor; the #1 pump motor is connected in series after the main contact of contactor KM1, and the #2 pump motor is connected in series after the main contact of contactor KM2; the control circuit includes a transformer, a pump motor stop button, a #1 pump motor start button, a #2 pump motor start button, a reset button, a pressure relay KP, a time relay KT, a relay K1, and a relay K2; the output terminal of the transformer is connected in series with the normally closed contact of the pump motor stop button, serving as the overall on / off control of the control circuit; the output terminal of the transformer is also connected to the common terminal of the coils of contactors KM1, KM2, K1, K2, and KT respectively; the normally open contact of the #1 pump motor start button... The normally open auxiliary contact of the start button for pump motor #1 is connected in parallel with the first auxiliary normally closed contact of contactor KM1, then connected in series with the first auxiliary normally closed contact of contactor KM2, and finally connected to the coil of contactor KM2, forming the self-locking and interlocking circuit for starting pump motor #1. The normally open contact of the start button for pump motor #2 is connected in parallel with the first auxiliary normally open contact of contactor KM2, then connected in series with the first auxiliary normally closed contact of contactor KM1, and finally connected to the coil of contactor KM2, forming the self-locking and interlocking circuit for starting pump motor #2. Pressing any start button can start the corresponding pump motor and form a self-locking circuit, while simultaneously preventing the start of another pump motor through the interlocking contact.

[0007] Furthermore, the normally open contact of the pressure relay KP is connected in series with the coil of the time relay KT; when the pressure relay KP is closed, the time relay KT starts timing, and only after the timing reaches the set value, the normally open contact of the time relay KT closes and outputs a switching trigger signal.

[0008] Furthermore, when the hydraulic system pressure corresponding to the running pump motor is lower than the preset value and the duration reaches the set time of the time relay KT, the switching logic is triggered to stop the currently running pump motor and start the standby pump motor. After the switching is completed, the current operating state is locked through the self-locking contact of relay K1 or relay K2, and automatic switching is prohibited again until the reset button is pressed to unlock.

[0009] Furthermore, when contactor KM1 is energized and time relay KT is activated, current flows through the auxiliary normally open contact of contactor KM1, the normally closed contact of relay K2, and the normally open contact of time relay KT, thus energizing the coil of relay K1.

[0010] Furthermore, when contactor KM2 is energized and time relay KT is activated, current flows through the auxiliary normally open contact of contactor KM2, the normally closed contact of relay K1, and the normally open contact of time relay KT, thus energizing the coil of relay K2.

[0011] Furthermore, after the relay K1 is energized, its first normally open contact closes to conduct the coil of contactor KM2 to start pump motor #2, while its normally closed contact opens to disconnect the coil of contactor KM1 to stop pump motor #1.

[0012] Furthermore, after the relay K2 is energized, its first normally open contact closes to conduct the coil of contactor KM1 to start pump motor #1, while its normally closed contact opens to disconnect the coil of contactor KM2 to stop pump motor #2.

[0013] Furthermore, relays K1 and K2 are each provided with a second normally open contact for self-holding; the normally closed contact of the reset button is connected in series in the self-holding circuit of relays K1 and K2; when relay K1 or relay K2 is energized and self-locked, even if the time relay KT is activated again, the other relay cannot be energized because the interlocking normally closed contact of relay K1 or relay K2 is open, thus prohibiting reverse switching until the reset button is pressed to cut off the self-holding circuit.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. Improve switching stability: By setting a time relay KT, switching is only triggered when the low pressure signal lasts for a set time, effectively filtering out false switching caused by instantaneous pressure fluctuations in the hydraulic system and avoiding frequent start-stop of the pump unit.

[0016] 2. Preventing Oscillation Switching: Through the self-locking logic of relays K1 and K2, once a fault switch is completed, the system is locked in the current operating pump state. Even if the pressure fluctuates again, it will not automatically switch back to the original faulty pump or repeatedly switch between the two pumps. The switching function will only be restored after the fault is confirmed to be eliminated by manually pressing the reset button, thus ensuring equipment safety.

[0017] 3. Flexible backup logic: When any pump starts, it becomes the master pump, and the other automatically becomes the backup pump. There is no need to pre-set the master-slave relationship through a selection switch, which simplifies the operation process and reduces the risk of human error.

[0018] 4. Simple and reliable circuit: Only three relays (two general-purpose relays and one time relay) are needed to implement complex redundant control and protection logic. There are fewer components, the failure rate is low, and maintenance is easy.

[0019] In summary, the dual-pump motor starting device of the present invention, which uses the controllable pitch propeller as a backup for each other, only adds three relays and achieves various functions of complex dual-pump motor redundant control through simple interlocking, self-protection and symmetrical circuit design. The device consists of three relays: two general-purpose relays and one time relay. The time relay ensures the reliability of acquiring low hydraulic supply pressure signals. General-purpose relay K1 ensures that when low supply pressure occurs while pump #1 is running, the system switches to pump #2. Relay K1's self-holding circuit prevents further switching while pump #2 is running. Pressing the reset button cancels relay K1's pump #2 running hold function and restores the device's switching function. Similarly, relay K2 ensures that when low supply pressure occurs while pump #2 is running, the system switches to pump #1. Relay K2's self-holding circuit prevents further switching while pump #1 is running until the reset button is pressed, canceling relay K2's pump #1 running hold function and restoring the device's switching function. This device has a simple and reliable design principle. It not only achieves various functions of redundant control of dual pump motors with mutual backup, but also has few components, facilitating fault maintenance and improving equipment reliability. Attached Figure Description

[0020] Figure 1 This is a simplified schematic diagram of the dual-pump motor starting device of the present invention, in which the controllable pitch propellers serve as backups for each other. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1As shown in the figure, an embodiment of the present invention provides a dual-pump motor starting device with mutually redundant controllable pitch propellers, comprising: a main power switch Q, a #1 pump motor switch Q1, a #2 pump motor switch Q2, fuses KR1 and KR2, a #1 pump motor YD1 and a #2 pump motor YD2, a transformer T, fuses F1 to F4, contactors KM1 and KM2, a #1 pump motor start button SB1, a #2 pump motor start button SB2, a pump motor stop button SB3, a reset button SB4, relays K1 and K2, a time relay KT, and a pressure relay KP, etc.

[0023] The three-phase input terminals of the main power switch Q are connected to an external three-phase 380VAC power supply. Its three-phase output terminals are connected in parallel to the three-phase input terminals of power switches Q1 and Q2 for pump motor #1 and pump motor #2, respectively. Two phases of these outputs are connected to the two-phase input terminals of transformer T after passing through fuses F1 and F2. The three-phase output terminals of power switch Q1 for pump motor #1 are connected to the input terminals of the main contacts of contactor KM1. The output terminals of the main contacts are connected to the upper terminals of fuse KR1. The lower terminals of fuse KR1 are connected to the incoming terminals U1, V1, and W1 of pump motor YD1. The three-phase output terminals of power switch Q2 for pump motor #2 are connected to the three-phase input terminals of contactor KM2. The input terminals of the main contacts are connected to the upper terminals of the fuse KR2, and the lower terminals of the fuse KR2 are connected to the input terminals U2, V2, and W2 of the #2 pump motor YD2. The two output terminals of the transformer T are connected to fuses F3 and F4 respectively. One phase is connected to the normally closed contact SB3.1 of the pump motor stop button SB3, and the other phase is connected in parallel, connecting to the coil terminals KM1.2, KM2.2, K1.2, K2.2, and KT.2 of the time relays KT and KM1.2 respectively. The normally closed contact terminal SB3 of the stop button SB3 is connected to the upper terminal of the fuse KR2, and the lower terminal of the fuse KR2 is connected to the input terminals U2, V2, and W2 of the pump motor YD2. The normally closed contact terminal SB3 of the stop button SB3 is connected to the input terminals U2, V2, and W2 of the pump motor YD2. 3.2 Parallel connection: Connect the normally open terminal SB1.1 of the start button SB1 for pump #1, the upper terminal of the first auxiliary normally open contact KM1_1 of contactor KM1, the normally open contact terminal SB2.2 of the start button SB2 for pump #2, the upper terminal of the first auxiliary normally open contact KM2_1 of contactor KM2, the upper terminal of the first normally open contact K1_1 of relay K1, the upper terminal of the first normally open contact K2_1 of relay K2, the upper terminal of the second auxiliary normally open contact KM1_2 of contactor KM1, the upper terminal of the second normally closed contact SB4_2 of reset button SB4, the upper terminal of the second auxiliary normally open contact KM2_2 of contactor KM2, and the oil supply... The normally open terminal KP.1 of the system pressure relay KP and the normally open terminal SB1.2 of the #1 pump motor start button SB1 are connected in parallel to the upper terminal of the first auxiliary normally closed contact KM2-1 of contactor KM2 and the lower terminal of the first auxiliary normally open contact KM1_1 of contactor KM1, respectively. The lower terminal of the first auxiliary normally closed contact KM2-1 of contactor KM2 is connected in parallel to the auxiliary fuse contact terminal KR1.1 of fuse KR1 and the lower terminal of the first normally open contact K2_1 of relay K2. The auxiliary fuse contact KR1.2 of fuse KR1 is connected to the terminal KM1.1 of the contactor KM1 coil; the normally open terminal SB2 of the #2 pump motor start button SB2.2. Connect in parallel: Connect the upper terminal of the first auxiliary normally closed contact KM1-1 of contactor KM1 to the lower terminal of the first auxiliary normally open contact KM2_1 of contactor KM2. The lower terminal of the first auxiliary normally closed contact KM1-1 of contactor KM1 is connected in parallel to the auxiliary fusible contact terminal KR2.1 of fuse KR2 and the lower terminal of the first normally open contact K1_1 of relay K1. The auxiliary fusible contact terminal KR2.2 of fuse KR2 is connected to the terminal KM2.1 of the coil of contactor KM2. The lower terminal of the auxiliary second normally open contact KM1_2 of contactor KM1 is connected to the upper terminal of the first normally closed contact SB4_1 of reset button SB4. The lower terminal of the first normally closed contact SB4_1 of reset button SB4 is connected to the upper terminal of the first normally closed contact K2-1 of relay K2. The lower terminal of the first normally closed contact K2-1 of relay K2 is connected to the upper terminal of the first normally open contact KT_1 of time relay KT. The lower terminals of the first normally open contact KT_1 of time relay KT are connected in parallel to the K1.1 terminal of relay K1 coil and the lower terminal of the second normally open contact K1_2 of relay K1, respectively. The lower terminal of the auxiliary second normally open contact KM2_2 of contactor KM2 is connected to the third terminal of reset button SB4. The upper terminal of the normally closed contact SB4_3 and the lower terminal of the third normally closed contact SB4_3 of the reset button SB4 are connected to the upper terminal of the first normally closed contact K1-1 of the relay K1. The lower terminal of the first normally closed contact K1-1 of the relay K1 is connected to the upper terminal of the second normally open contact KT_2 of the time relay KT. The lower terminal of the second normally open contact KT_2 of the time relay KT is connected in parallel and is respectively connected to the K2.1 terminal of the coil of the relay K2 and the lower terminal of the second normally open contact K2_2 of the relay K2. The lower terminal of the second normally closed contact SB4_2 of the reset button SB4 is connected in parallel and is respectively connected to the upper terminal of the second normally open contact K1_2 of the relay K1 and the upper terminal of the second normally open contact K2_2 of the relay K2.

[0024] The dual-pump motor starting device, which serves as a backup for the controllable pitch propeller, includes the following functions: 1) Start either of the two pump motors, and that motor will become the main working pump motor, while the other pump motor will be stopped and in standby mode. Only one of the two pump motors can be started and running at a time. When the main power switch Q, the switch for pump #1 motor Q1, and the switch for pump #2 motor Q2 are closed, the external three-phase 380VAC power supply passes through each switch and enters the three-phase main input contacts of contactor KM1, the three-phase main input contacts of contactor KM2, and the two-phase input terminals of transformer T. Through the transformer T's transformation action, two-phase 24VAC AC control power is output from the output terminal of transformer T. This power then passes through the fuse and the normally closed contact of the pump motor stop button SB3, and enters the normally open contacts of the pump #1 motor start button SB1 and the pump #2 motor start button SB2, respectively. When pump #1... When the motor start button SB1 is pressed, its normally open contact closes, and the 24V AC control power enters the coil of contactor KM1 through the first auxiliary normally closed contact of contactor #2 and the auxiliary closed contact of fuse #1. After the coil of contactor KM1 is energized, the three-phase main contacts of contactor KM1 close, and at the same time, its auxiliary normally open contact closes and its auxiliary normally closed contact opens. The first auxiliary normally open contact of contactor KM1 closes to achieve circuit self-holding. The first auxiliary normally closed contact of contactor KM1 opens to achieve circuit interlock between contactor KM1 and contactor KM2, that is, to ensure that the two pump motors cannot start and run at the same time. Simultaneously, when the coil of contactor KM1 is energized and its three-phase main contacts close, external three-phase 380V AC power enters pump motor YD1 through the three-phase main contacts of contactor KM1 and fuse KR1, energizing and starting pump motor YD1. At this time, pump motor YD1 is the main motor, while pump motor YD1 is not energized and is in standby mode. Similarly, when the start button SB2 of pump motor YD1 is pressed, its normally open contact closes, and 24V AC control power enters the coil of contactor KM2 through the first auxiliary normally closed contact of contactor KM1 and the auxiliary closed contact of fuse YD1. When the coil of contactor KM2 is energized, the three-phase main contacts of contactor KM2 close, and its auxiliary normally open contact closes while its auxiliary normally closed contact opens. The first auxiliary normally open contact of contactor KM2 closes to achieve circuit self-protection, and the first auxiliary normally closed contact of contactor KM2 opens to achieve circuit interlock between contactor KM2 and contactor KM1, thus ensuring that the two pump motors cannot start and run simultaneously. At the same time, the coil of contactor KM2 is energized, and after its three-phase main contacts are closed, the external three-phase 380 AC power enters the No. 2 pump motor YD2 through the three-phase main contacts of contactor KM2 and fuse KR2. The No. 2 pump motor is energized and starts running. At this time, the No. 2 pump motor is the main motor, and the No. 1 pump motor is not energized and is in standby mode. 2) When the pressure of the power oil supply system is low, after a delay to ensure that the low pressure signal is correctly collected, the main working pump motor stops working, and another pump motor as a backup starts to run. After closing the main power switch Q, the switch for pump #1 motor Q1, and the switch for pump #2 motor Q2; press the start button SB1 for pump #1 motor to start pump #1 motor, while pump #2 motor is in standby stop state. At this time, contactor KM1 is energized, and all its auxiliary normally closed contacts are closed. When the normally open contact of the oil supply system pressure relay KP closes due to low oil supply system pressure, two-phase 24VAC AC control current enters the coil of the time relay KT through the contacts of the pressure relay KP. When the low pressure duration reaches the set time of the time relay KT, all normally open contacts of the time relay KT close. At this time, two-phase 24VAC AC control current enters the coil of relay K1 through the first auxiliary normally open contact KM1_1 of contactor KM1, the normally closed contact K2_2 of relay K2, and the normally open contact of the time relay KT, energizing relay K1. At this time, all normally open contacts of relay K1 close, the normally closed contacts open, the second normally open contact of relay K1 closes (circuit self-holding), and the first normally closed contact of relay K1 opens (circuit interlocking between relay K1 and relay K2). After the open contact closes, the two-phase 24VAC control power enters the coil of contactor KM2 through the first normally open contact K1_1 of relay K1 and the closed contact of fuse KR2, energizing contactor KM2. At this time, the three-phase main contacts of contactor KM2 close, and all its auxiliary normally open contacts close and normally closed contacts open. The three-phase main contacts of contactor KM2 close, and the external 380V three-phase AC power enters the #2 pump motor YD2 through contactor KM2 and fuse KR2. The #2 pump motor is energized and starts, entering the running state. At the same time, the first auxiliary normally closed contact KM2-1 of contactor KM2 opens, causing contactor KM1 to lose power. This causes the three-phase main contacts of contactor KM1 to open, causing the #1 pump motor YD1 to lose power and enter the stop state, realizing the automatic switching function between the two pump motors when the oil supply system pressure is low. Similarly, pressing the start button SB2 for pump #2 starts pump #2, while pump #1 remains in standby stop mode. At this time, contactor KM2 is energized, and all its normally closed auxiliary contacts close. When the normally open contact of the oil supply system pressure relay KP closes due to low oil supply system pressure, two-phase 24VAC AC control current enters the coil of the time relay KT through the contacts of the pressure relay KP. When the low pressure duration reaches the set time of the time relay KT, all normally open contacts of the time relay KT close. At this time, two-phase 24VAC AC control current enters the coil of relay K2 through the first auxiliary normally open contact KM2_1 of contactor KM2, the normally closed contact K1_2 of relay K1, and the normally open contact of the time relay KT, energizing relay K2. At this time, all normally open contacts of relay K2 close, the normally closed contacts open, the second normally open contact of relay K2 closes (circuit self-holding), and the first normally closed contact of relay K2 opens (circuit interlocking between relay K2 and relay K1). After the open contact closes, the two-phase 24VAC control power enters the coil of contactor KM1 through the first normally open contact K2_1 of relay K2 and the closed contact of fuse KR1, energizing contactor KM1. At this time, the three-phase main contacts of contactor KM1 close, and all its auxiliary normally open contacts close and normally closed contacts open. The three-phase main contacts of contactor KM1 close, and the external 380V three-phase AC power enters pump motor YD1 of pump #1 through contactor KM1 and fuse KR1. Pump motor #1 is energized and starts, entering the running state. At the same time, the first auxiliary normally closed contact KM1-1 of contactor KM1 opens, causing contactor KM2 to lose power. This causes the three-phase main contacts of contactor KM2 to open, causing pump motor YD2 of pump #2 to lose power and enter the stop state. This realizes the automatic switching function between the two pump motors when the oil supply system pressure is low. 3) Due to low pressure in the power oil supply system, after switching between the two pump motors, the currently operating pump motor will remain in operation. If the oil supply system pressure is low again, the switching cannot be performed again. When the reset button is pressed, the operating pump motor will be unlocked, and the switching between the two pump motors can be performed again when the oil supply system pressure is low. When pump #1 switches to pump #2 due to low oil supply system pressure, pump #2 is in operation. Simultaneously, relay K1 is energized, all its normally closed contacts open, and its normally open contacts close. The second normally open contact K1_2 of relay K1 closes, enabling the circuit to maintain its self-holding function. At this point, the oil supply system pressure returns to normal. Even after all normally open contacts of time relay KT open, relay K1 remains energized, ensuring the normal operation of pump #2 (YD2). At the same time, the first normally closed contact of relay K1 opens, interlocking the circuits of relays K1 and K2. If the power supply system pressure drops again (i.e., all normally open contacts of time relay KT close), relay K2 will also fail to energize, preventing pump #1 from starting and thus preventing switching between the two pumps. Theoretically, when pump #2 switches to pump #1 due to low oil supply system pressure, pump #1 is in operation. Simultaneously, relay K2 is energized, all its normally closed contacts open, and its normally open contacts close. The second normally open contact K2_2 closes, enabling the circuit to self-hold. At this point, the oil supply system pressure returns to normal. Even after all normally open contacts of time relay KT open, relay K2 remains energized, ensuring the normal operation of pump #1 (YD1). At the same time, the first normally closed contact of relay K2 opens, interlocking the circuits of relay K2 and relay K1. If the power supply system pressure drops again (i.e., all normally open contacts of time relay KT close), relay K1 cannot be energized, and pump #2 cannot start, meaning switching between the two pumps cannot occur. After the low-pressure switching of the oil supply system between the two pumps is completed, press the reset button SB4. Both relays K1 and K2 will be de-energized, and their self-protection function will fail. Relays K1 and K2 will enter a waiting state for low system pressure and prepare to be energized. If a low oil supply system pressure occurs at this time, the switching function between the two pump motors can be restored.

[0025] Finally, it should be noted that the above examples are merely a few specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A dual-pump motor starting device with adjustable-pitch propellers serving as backups for each other, characterized in that, The system includes a main power supply circuit and a control circuit. The main power supply circuit includes a main power switch, a switch for pump motor #1, a switch for pump motor #2, contactors KM1 and KM2, pump motor #1, and pump motor #2. Pump motor #1 is connected in series after the main contacts of contactor KM1, and pump motor #2 is connected in series after the main contacts of contactor KM2. The control circuit includes a transformer, a pump motor stop button, a pump motor start button, a pump motor #2 start button, a reset button, a pressure relay KP, a time relay KT, relay K1, and relay K2. The output terminal of the transformer is connected in series with the normally closed contact of the pump motor stop button, serving as the overall on / off control of the control circuit. The output terminal of the transformer is also connected to the common terminal of the coils of contactors KM1 and KM2, relays K1 and K2, and the time relay KT. The normally open contact of the pump motor start button... The normally open auxiliary contact of the start button for pump motor #1 is connected in parallel with the first auxiliary normally closed contact of contactor KM1, then connected in series with the first auxiliary normally closed contact of contactor KM2, and finally connected to the coil of contactor KM2, forming the self-locking and interlocking circuit for starting pump motor #1. The normally open contact of the start button for pump motor #2 is connected in parallel with the first auxiliary normally open contact of contactor KM2, then connected in series with the first auxiliary normally closed contact of contactor KM1, and finally connected to the coil of contactor KM2, forming the self-locking and interlocking circuit for starting pump motor #2. Pressing any start button can start the corresponding pump motor and form a self-locking circuit, while simultaneously preventing the start of another pump motor through the interlocking contact.

2. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 1, characterized in that, The normally open contact of the pressure relay KP is connected in series with the coil of the time relay KT. When the pressure relay KP is closed, the time relay KT starts timing. Only after the timing reaches the set value will the normally open contact of the time relay KT close and output a switching trigger signal.

3. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 2, characterized in that, When the hydraulic system pressure corresponding to the running pump motor is lower than the preset value and the duration reaches the set time of the time relay KT, the switching logic is triggered to stop the currently running pump motor and start the standby pump motor. After the switching is completed, the current operating state is locked through the self-locking contact of relay K1 or relay K2, and automatic switching is prohibited again until the reset button is pressed to unlock.

4. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 1, characterized in that, When contactor KM1 is energized and time relay KT is activated, current flows through the auxiliary normally open contact of contactor KM1, the normally closed contact of relay K2, and the normally open contact of time relay KT, thus energizing the coil of relay K1.

5. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 1, characterized in that, When contactor KM2 is energized and time relay KT is activated, current flows through the auxiliary normally open contact of contactor KM2, the normally closed contact of relay K1, and the normally open contact of time relay KT, thus energizing the coil of relay K2.

6. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 1, characterized in that, When relay K1 is energized, its first normally open contact closes to conduct the coil of contactor KM2 to start pump motor #2, and at the same time its normally closed contact opens to disconnect the coil of contactor KM1 to stop pump motor #1.

7. The dual-pump motor starting device with mutually redundant controllable pitch propellers according to claim 1, characterized in that, When relay K2 is energized, its first normally open contact closes to conduct the coil of contactor KM1 to start pump motor #1, and at the same time its normally closed contact opens to disconnect the coil of contactor KM2 to stop pump motor #2.

8. The dual-pump motor starting device with alternating pitch propellers as backups for each other, as described in claim 1, is characterized in that, Relays K1 and K2 are each provided with a second normally open contact for self-holding; the normally closed contact of the reset button is connected in series in the self-holding circuit of relays K1 and K2; when relay K1 or relay K2 is energized and self-locked, even if the time relay KT is activated again, the other relay cannot be energized because the interlocking normally closed contact of relay K1 or relay K2 is open, thus prohibiting reverse switching until the reset button is pressed to cut off the self-holding circuit.

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