Fire fighting water pump starting control system

Abstract

The application discloses a fire-fighting water pump starting control system, which comprises a main circuit and a secondary control circuit, and a plurality of fire-fighting pumps arranged on the same fire-fighting pipeline; the power input end of the main circuit is connected with an alternating power source; the power output end of the main circuit supplies power for the motors of the plurality of fire-fighting pumps; the secondary control circuit is used for generating a control signal according to a control instruction; and the main circuit controls the plurality of fire-fighting pumps to realize star-delta switching one by one by staggering the star-delta switching time, so as to reduce the starting current of the plurality of fire-fighting pumps as a whole. The system replaces the original single high-power fire-fighting water pump with three or two small-power fire-fighting water pumps, and then avoids the switching time of the three or two small-power fire-fighting water pumps from being staggered, so that the starting current is reduced as a whole, the great impact on the motors is avoided, the service life of the motors is influenced, and the maintenance cost of the fire-fighting water pump is reduced.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment control technology, specifically to a fire pump start-up control system. Background Technology

[0002] Fire pumps are the core power equipment of substation fire water supply systems. Currently, most fire pump motors in substations operate at a constant speed, meaning they run at full speed from startup. This operating mode generates a peak current several times the rated current at startup, causing significant thermal stress and mechanical impact on the motor winding insulation and mechanical bearings. Over time, this accelerates insulation aging and bearing wear, severely shortening the motor's lifespan and increasing equipment replacement and maintenance costs.

[0003] Regarding the starting control strategy for fire pumps, current substation fire pumps generally use a single high-power motor paired with a star-delta starting device. This starting method generates a short-term overcurrent surge during the instantaneous switch from star to delta connection. This surge current can not only cause the station's service transformer to trip prematurely, but also disturb the voltage stability of the substation's microgrid system, affecting the reliable operation of other protection devices. More critically, this starting defect may trigger protective actions on the power grid side, causing the fire pump to fail to start normally or stop midway in emergency fire conditions, creating a significant fire safety vulnerability.

[0004] Therefore, there is an urgent need to provide a motor starting control scheme that can suppress starting current surges and improve the operational reliability and service life of fire pumps. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a fire pump start-up control system to solve the problem of excessive starting current when high-lift fire pump motors are required in substations and other locations.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A fire pump starting control system, the key features of which are: a main circuit and a secondary control circuit, and several fire pumps installed on the same fire pipeline; the power input terminal of the main circuit is connected to an AC power source, and the power output terminal of the main circuit supplies power to the motors of several fire pumps; the secondary control circuit is used to generate control signals according to control commands; and the main circuit controls several fire pumps to complete star-delta switching sequentially by staggering the star-delta switching times according to the control signals, so as to reduce the overall starting current of several fire pumps.

[0007] Furthermore, the main circuit includes a main circuit breaker, a step-up converter, multiple first contactors, multiple second contactors, and multiple third contactors. The input terminal of the main circuit breaker is connected to an AC power source, and the output terminal of the main circuit breaker is connected to the input terminal of the step-up converter. The output terminal of the step-up converter outputs three-phase power to supply power to the motors of each fire pump. One end of the main contact of the first contactor is connected to the output terminal of the step-up converter, and the other end of the main contact of the first contactor is connected to the first port of the fire pump motor and one end of the main contact of the third contactor. The second port of the fire pump motor and the other end of the main contact of the third contactor are both connected to the second contactor.

[0008] Furthermore, the secondary control loop includes a controller, a system start-up unit and a system stop-down unit connected to the controller input terminal group, and several start-up control circuits connected to the controller output terminal group; The system startup unit is used to output startup control commands; the system stop unit is used to output stop control commands. The controller is used to generate a start control signal according to the start control command, and is also used to generate a stop control signal according to the stop control command; Several of the aforementioned start control circuits are connected one-to-one with the motors of several fire pumps to control the start mode of the fire pump motors in response to the start control signal, and to disconnect the power supply path of each fire pump motor in response to the stop control signal.

[0009] Furthermore, the start-up control circuit includes a timer. The coil winding of the first contactor is connected between the first output terminal of the controller and the neutral line. One end of the normally open switch of the first contactor is connected to the second output terminal of the controller, and the other end of the normally open switch of the first contactor is connected to the first output terminal of the controller. The first output terminal of the controller is also connected in series with the normally closed switch of the third contactor and the normally closed switch of the timer, and then connected to the neutral line through the coil winding of the second contactor. One end of the coil winding of the timer is connected to the common terminal of the normally closed switch of the third contactor and the normally closed switch of the timer, and the other end of the coil winding of the timer is connected to the neutral line. The first output terminal of the controller is also connected in series with the normally closed switch of the second contactor and the normally open switch of the timer, and then connected to the neutral line through the coil winding of the third contactor. The normally open switch of the third contactor and the normally open switch of the timer are connected in parallel.

[0010] Furthermore, the start-up control circuit also includes a fourth contactor and a fifth contactor. The normally open switch of the fourth contactor and the normally closed switch of the fifth contactor are integrated into the controller. The coil windings of the fourth and fifth contactors are connected to the power supply circuit of the controller. One end of the normally open switch of the fourth contactor is connected in series with the normally closed switch of the fifth contactor and then connected to the live wire. The other end of the normally open switch of the fourth contactor is connected in series with the coil winding of the first contactor and then connected to the neutral wire. The normally open switch of the first contactor and the normally open switch of the fourth contactor are connected in parallel.

[0011] Furthermore, the delay duration of the delay device corresponding to each of the fire pumps is different.

[0012] Furthermore, the system start-up unit uses a start button, and the system stop-stop unit uses a stop button. The start button and stop button are connected to the two signal input terminals of the controller.

[0013] Furthermore, the controller is connected to a display screen for outputting the current curve waveform.

[0014] Furthermore, the main circuit also includes a DC power supply, the input terminal group of which is connected to the output terminal of the main circuit breaker, and the output terminal group of which is connected to the power input terminal group of the controller in the secondary control circuit.

[0015] Furthermore, the main circuit also includes a current transmitter, the power input terminal group of which is connected to the output terminal group of the DC power supply, the signal input terminal of which is used to sample any one phase of the three-phase power output by the boost converter, and the signal output terminal of which is connected to the controller in the secondary control circuit.

[0016] The significant effects of this invention are: 1. This invention uses a soft-start method to control the fire pump motor. By gradually increasing the output voltage and frequency, the motor is smoothly accelerated to the rated speed, effectively suppressing the peak current impact at the moment of startup. This avoids the damage to the motor insulation and bearings caused by the large current in constant speed start and star-delta start methods, significantly extending the service life of the fire pump starter motor, reducing the frequency of equipment maintenance and replacement, and saving operation and maintenance costs.

[0017] 2. This invention eliminates the overcurrent surge generated during star-delta start-up switching and the risk of over-tripping of station service transformers, avoids interference with the voltage stability of the microgrid within the station, ensures the normal operation of other protection devices and electrical equipment in the substation, and improves the overall stability and power supply reliability of the station service system.

[0018] 3. This invention eliminates the safety hazards of startup failure through smooth start-up, ensuring that the fire pump can be reliably started and run continuously in emergency fire conditions, eliminating the phenomenon of motor shutdown or failure to start due to startup current surge, thus guaranteeing the emergency response capability of the fire water supply system from the source and eliminating fire safety loopholes.

[0019] 4. The control strategy of this invention is flexible and can be adapted to fire pump motors of different power levels. It has good compatibility and versatility for the transformation of existing substation fire pump control cabinets, has low implementation cost, and is easy to promote and apply in power systems and related industrial fields. Attached Figure Description

[0020] Figure 1 This is the circuit diagram of the main circuit in this invention; Figure 2 This is the circuit diagram of the secondary control loop in this invention; Figure 3 This is the interface diagram of the controller in this invention. Detailed Implementation

[0021] The specific embodiments and working principles of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Example: This example illustrates how to replace a single high-power water pump with three low-power water pumps: In other words, the fire pump start-up control system described in this example includes three fire pumps installed on the same fire pipeline, as well as a main circuit and a secondary control circuit. The power input terminal of the main circuit is connected to an AC power source, and the power output terminal of the main circuit supplies power to the motors of several fire pumps. The secondary control circuit generates control signals according to control commands. The main circuit controls several fire pumps to sequentially complete the star-delta switching by staggering the star-delta switching times, thereby reducing the overall starting current of several fire pumps. Specifically: Please refer to the circuit principle of the main circuit. Figure 1It includes a main circuit breaker QF1, a step-up converter BCP1, multiple first contactors (KM11~KM31), multiple second contactors (KM12~KM32), and multiple third contactors (KM13~KM33). The input terminal of the main circuit breaker QF1 is connected to a 220V AC power supply, and the output terminal of the main circuit breaker QF1 is connected to the input terminal of the step-up converter BCP1. The output terminal of the step-up converter BCP1 outputs 380V three-phase power to power the motors of three fire pumps. One end of the main contact of the first contactor is connected to the output terminal of the step-up converter BCP1, and the other end of the main contact of the first contactor is connected to the first port of the three fire pump motors and one end of the main contact of the third contactor. The second port of the fire pump motors and the other end of the main contact of the third contactor are both connected to the second contactors.

[0023] Based on the above content and appendix Figure 1 It can be seen that the specific wiring method for each fire pump motor is as follows: For fire pump #1: the first port U11, V11, W11 of the fire pump motor is connected to the other end of the main contact of the first contactor KM11, the main contact of the second contactor KM12 is connected to the second port U12, V12, W12 of the fire pump motor, and the two ends of the main contact of the third contactor KM13 are connected to the first port U11, V11, W11 and the second port U12, V12, W12 of the fire pump motor, respectively. For fire pump #2: the first port U21, V21, W21 of the fire pump motor is connected to the other end of the main contact of the first contactor KM21, the main contact of the second contactor KM22 is connected to the second port U22, V22, W22 of the fire pump motor, and the two ends of the main contact of the third contactor KM23 are connected to the first port U21, V21, W21 and the second port U22, V22, W22 of the fire pump motor, respectively. For fire pump #3: the first port U31, V31, W31 of the fire pump motor is connected to the other end of the main contact of the first contactor KM31. The main contact of the second contactor KM32 is connected to the second port U32, V32, W32 of the fire pump motor. The two ends of the main contact of the third contactor KM33 are connected to the first port U31, V31, W31 and the second port U32, V32, W32 of the fire pump motor, respectively.

[0024] from Figure 1 It can also be seen that the main circuit also includes a DC power supply AV1, the input terminal group of which is connected to the output terminal of the main circuit breaker QF1, and the output terminal group of which is connected to the power input terminal group C24 and C00 of the controller in the secondary control circuit.

[0025] The aforementioned DC power supply AV1 converts 220V AC power into DC power to supply power to the controller of the secondary control circuit.

[0026] To facilitate monitoring of the current of each fire pump, the main circuit also includes a current transmitter BPA1. The power input terminal group of the current transmitter BPA1 is connected to the output terminal group of the DC power supply AV1. The signal input terminal of the current transmitter BPA1 is used to sample any phase of the three-phase power output by the boost converter BCP1. The signal output terminal of the current transmitter BPA1 is connected to the current acquisition signal input terminals AD+ and AD- of the controller in the secondary control circuit. The controller is equipped with a display screen for outputting the current curve waveform.

[0027] The aforementioned current transmitter BPA1 is a current measurement and extraction unit that transmits current to the controller and display screen, allowing them to output the current curve waveform on the display screen. In implementation, the standard fire protection system uses a direct 380V input, but a 220V to 380V conversion can also be used. In this example, the boost converter BCP1 can be a 220V to 380V transformer.

[0028] In this example, the secondary control loop includes a controller, a system start-up unit and a system stop unit connected to the controller input terminal group, and several start-up control circuits connected to the controller output terminal group. The system startup unit is used to output startup control commands; the system stop unit is used to output stop control commands. The controller is a PLC controller, used to generate a start control signal according to the start control command, and also used to generate a stop control signal according to the stop control command; Several of the aforementioned start control circuits are connected one-to-one with the motors of several fire pumps to control the start mode of the fire pump motors in response to the start control signal, and to disconnect the power supply path of each fire pump motor in response to the stop control signal.

[0029] like Figure 2 and Figure 3As shown, the system start unit uses a start button SA1, and the system stop unit uses a stop button SA2. The start button SA1 and stop button SA2 are connected to the two signal input terminals DI1 and DI2 of the controller. The start control circuit includes timers (KT1, KT2, KT3). The coil winding of the first contactor is connected between the first output terminal of the controller and the neutral line N1. One end of the normally open switch of the first contactor is connected to the second output terminal of the controller, and the other end of the normally open switch of the first contactor is connected to the first output terminal of the controller. The first output terminal of the controller is also connected in series with the normally closed switch of the third contactor and the normally closed switch of the timer, and then connected to the neutral line N1 through the coil winding of the second contactor. One end of the coil winding of the timer is connected to the common terminal of the normally closed switch of the third contactor and the normally closed switch of the timer, and the other end of the coil winding of the timer is connected to the neutral line N1. The first output terminal of the controller is also connected in series with the normally closed switch of the second contactor and the normally open switch of the timer, and then connected to the neutral line through the coil winding of the third contactor. The normally open switch of the third contactor and the normally open switch of the timer are connected in parallel.

[0030] Furthermore, the start-up control circuit also includes a fourth contactor (KA1, KA3, KA5) and a fifth contactor (KA2, KA4, KA6). The normally open switch of the fourth contactor and the normally closed switch of the fifth contactor are integrated into the controller. The coil windings of the fourth and fifth contactors are connected to the power supply circuit of the controller. One end of the normally open switch of the fourth contactor is connected in series with the normally closed switch of the fifth contactor and then connected to the live wire L1. The other end of the normally open switch of the fourth contactor is connected in series with the coil winding of the first contactor and then connected to the neutral wire N1. The normally open switch of the first contactor and the normally open switch of the fourth contactor are connected in parallel.

[0031] Based on the circuit description above, the starting control circuit for each fire pump motor is as follows: For fire pump #1: One end of the normally open switch of the fourth contactor KA1 is connected in series with one end of the normally closed switch of the fifth contactor KA2. The other end of the normally closed switch of the fifth contactor KA2 is connected to the live wire L1. The other end of the normally open switch of the fourth contactor KA1 is connected in series with the coil winding of the first contactor KM11 and then connected to the neutral wire N1. The normally open switch of the first contactor KM11 and the normally open switch of the fourth contactor KA1 are connected in parallel. That is, one end of the normally open switch of the first contactor KM11 is connected to the common terminal of the normally open switch of the fourth contactor KA1 and the normally closed switch of the fifth contactor KA2, and the other end of the normally open switch of the first contactor KM11 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally open switch of the first contactor KM11 is connected in series with the normally closed switch of the third contactor KM13 and the normally closed switch of the time delay KT1, and then connected to the neutral line N1 via the coil winding of the second contactor KM12. One end of the coil winding of the time delay KT1 is connected to the common terminal of the normally closed switch of the third contactor KM13 and the normally closed switch of the time delay KT1, and the other end of the coil winding of the time delay KT1 is connected to the neutral line N1. One end of the normally closed switch of the second contactor KM12 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally closed switch of the second contactor KM12 is connected in series with the normally open switch of the time delay KT1 and the coil winding of the third contactor KM13, and then connected to the neutral line N1. The normally open switch of the third contactor KM13 and the normally open switch of the time delay KT1 are connected in parallel. Based on the circuit described above, the principle of the start-up control circuit is as follows: When the start button SA1 is pressed, the normally open switch of the fourth contactor KA1 closes, energizing the first contactor KM11 below, and controlling the normally open switch of KM11 to close. The normally open switch of the first contactor KM11 closes, energizing the timer KT1 and starting the countdown. When KT1 is energized, the normally closed switch of KT1 on the second contactor KM12 closes, and the normally open switch of KT1 on the third contactor KM13 opens. The second contactor KM2 is a star-connected contactor. When the timer KT1 is energized, the coil winding of the second timer KM12 is energized, controlling the star-connected switch of the water pump, which is also the main contact of the second contactor, to close. At this time, the fire pump is connected in a star configuration. At the same time, the normally closed switch of the second contactor KM12 is opened to ensure that the coil windings of the star-connected second contactor KM12 and the delta-connected third contactor KM13 are not energized at the same time. After the countdown of the delay timer KT1 ends, the normally open switch controlling KT1 opens and the normally closed switch of KT1 closes, causing the coil winding of the second contactor KM12 to be de-energized. The normally open switch of the second contactor KM12 then returns to the closed position. At this time, the coil winding of the third contactor KM13 is energized, the main contacts of the third contactor KM13 close, and the fire pump switches to delta connection.

[0032] Pressing the stop button SA2 energizes the coil winding of the fifth contactor KA2, opens the normally closed switch of the fifth contactor KA2, disconnects the power supply, and shuts down the fire pump.

[0033] For fire pump #2: One end of the normally open switch of the fourth contactor KA1 is connected in series with one end of the normally closed switch of the fifth contactor KA2. The other end of the normally closed switch of the fifth contactor KA2 is connected to the live wire L1. The other end of the normally open switch of the fourth contactor KA1 is connected in series with the coil winding of the first contactor KM21 and then connected to the neutral wire N1. The normally open switch of the first contactor KM21 and the normally open switch of the fourth contactor KA1 are connected in parallel. That is, one end of the normally open switch of the first contactor KM21 is connected to the common terminal of the normally open switch of the fourth contactor KA1 and the normally closed switch of the fifth contactor KA2, and the other end of the normally open switch of the first contactor KM21 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally open switch of the first contactor KM21 is connected in series with the normally closed switch of the third contactor KM23 and the normally closed switch of the time delay KT2, and then connected to the neutral line N1 through the coil winding of the second contactor KM22. One end of the coil winding of the time delay KT2 is connected to the common terminal of the normally closed switch of the third contactor KM23 and the normally closed switch of the time delay KT2, and the other end of the coil winding of the time delay KT2 is connected to the neutral line N1. One end of the normally closed switch of the second contactor KM22 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally closed switch of the second contactor KM22 is connected in series with the normally open switch of the time delay KT2, the coil winding of the third contactor KM23, and then connected to the neutral line N1. The normally open switch of the third contactor KM23 and the normally open switch of the time delay KT2 are connected in parallel.

[0034] For fire pump #3: One end of the normally open switch of the fourth contactor KA1 is connected in series with one end of the normally closed switch of the fifth contactor KA2. The other end of the normally closed switch of the fifth contactor KA2 is connected to the live wire L1. The other end of the normally open switch of the fourth contactor KA1 is connected in series with the coil winding of the first contactor KM31 and then connected to the neutral wire N1. The normally open switch of the first contactor KM31 and the normally open switch of the fourth contactor KA1 are connected in parallel. That is, one end of the normally open switch of the first contactor KM31 is connected to the common end of the normally open switch of the fourth contactor KA1 and the normally closed switch of the fifth contactor KA2, and the other end of the normally open switch of the first contactor KM31 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally open switch of the first contactor KM31 is connected in series with the normally closed switch of the third contactor KM33 and the normally closed switch of the time delay KT3, and then connected to the neutral line N1 through the coil winding of the second contactor KM32. One end of the coil winding of the time delay KT3 is connected to the common terminal of the normally closed switch of the third contactor KM33 and the normally closed switch of the time delay KT3, and the other end of the coil winding of the time delay KT3 is connected to the neutral line N1. One end of the normally closed switch of the second contactor KM32 is connected to the other end of the normally open switch of the fourth contactor KA1. The other end of the normally closed switch of the second contactor KM32 is connected in series with the normally open switch of the time delay KT3, the coil winding of the third contactor KM33, and then connected to the neutral line N1. The normally open switch of the third contactor KM33 and the normally open switch of the time delay KT3 are connected in parallel.

[0035] In this specific implementation, the motors of the three fire pumps are connected in parallel. The first contactor installed on each pump is a star-delta time delay controller GRT8-A2, the second contactor is a star-connected control contactor, and the third contactor is a delta-connected control contactor. The first contactor is used to set the time for switching from star connection to delta connection to achieve peak-shifting and reduce starting current.

[0036] Furthermore, the delay duration of the timer KT1 corresponding to each fire pump is different. By using timers with different delay values, three fire pumps can be simultaneously connected to the power supply in a star connection and started, achieving peak-shifting switching, for example: Fire pump #1 is set to switch to delta connection after 7 seconds of star start; Fire pump #2 is set to switch to delta connection after 8 seconds of star start; Fire pump #3 is set to start in a star configuration and then switch to a delta configuration after 9 seconds.

[0037] In summary, the system described in this invention replaces the original single high-power fire pump with three or two low-power fire pumps. Since the large starting current of the fire pump after switching occurs only briefly, the first, second, and third contactors are started simultaneously. At this time, all three fire pumps will enter star connection operation. Their respective timers KT1, KT2, and KT3 start counting down simultaneously, with KT1 delaying for 7 seconds, KT2 for 8 seconds, and KT3 for 9 seconds. In this way, the current peaks of the three fire pumps after the star-delta switching will occur in staggered order, thereby reducing the overall starting current and avoiding a large impact on the motor, which would affect its service life. This also helps to reduce the maintenance cost of the fire pump.

[0038] The technical solution provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A fire pump start-up control system, characterized in that: It includes a main circuit and a secondary control circuit, as well as several fire pumps installed on the same fire protection pipeline. The power input terminal of the main circuit is connected to an AC power source, and the power output terminal of the main circuit supplies power to the motors of several fire pumps. The secondary control circuit is used to generate control signals according to control commands. The main circuit controls several fire pumps to complete the star-delta switching sequentially by staggering the star-delta switching times, so as to reduce the overall starting current of several fire pumps.

2. The fire pump start-up control system according to claim 1, characterized in that: The main circuit includes a main circuit breaker, a step-up converter, multiple first contactors, multiple second contactors, and multiple third contactors. The input terminal of the main circuit breaker is connected to an AC power source, and the output terminal of the main circuit breaker is connected to the input terminal of the step-up converter. The output terminal of the step-up converter outputs three-phase power to supply power to the motors of each fire pump. One end of the main contact of the first contactor is connected to the output terminal of the step-up converter, and the other end of the main contact of the first contactor is connected to the first port of the fire pump motor and one end of the main contact of the third contactor. The second port of the fire pump motor and the other end of the main contact of the third contactor are both connected to the second contactor.

3. The fire pump start control system according to claim 2, characterized in that: The secondary control loop includes a controller, a system start-up unit and a system stop unit connected to the controller input terminal group, and several start-up control circuits connected to the controller output terminal group. The system startup unit is used to output startup control commands; the system stop unit is used to output stop control commands. The controller is used to generate a start control signal according to the start control command, and is also used to generate a stop control signal according to the stop control command; Several of the aforementioned start control circuits are connected one-to-one with the motors of several fire pumps to control the start mode of the fire pump motors in response to the start control signal, and to disconnect the power supply path of each fire pump motor in response to the stop control signal.

4. The fire pump start-up control system according to claim 3, characterized in that: The start-up control circuit includes a timer. The coil winding of the first contactor is connected between the first output terminal of the controller and the neutral line. One end of the normally open switch of the first contactor is connected to the second output terminal of the controller, and the other end of the normally open switch of the first contactor is connected to the first output terminal of the controller. The first output terminal of the controller is also connected in series with the normally closed switch of the third contactor and the normally closed switch of the timer, and then connected to the neutral line through the coil winding of the second contactor. One end of the coil winding of the timer is connected to the common terminal of the normally closed switch of the third contactor and the normally closed switch of the timer, and the other end of the coil winding of the timer is connected to the neutral line. The first output terminal of the controller is also connected in series with the normally closed switch of the second contactor and the normally open switch of the timer, and then connected to the neutral line through the coil winding of the third contactor. The normally open switch of the third contactor and the normally open switch of the timer are connected in parallel.

5. The fire pump start-up control system according to claim 4, characterized in that: The start-up control circuit includes a fourth contactor and a fifth contactor. The normally open switch of the fourth contactor and the normally closed switch of the fifth contactor are integrated into the controller. The coil windings of the fourth and fifth contactors are connected to the power supply circuit of the controller. One end of the normally open switch of the fourth contactor is connected in series with the normally closed switch of the fifth contactor and then connected to the live wire. The other end of the normally open switch of the fourth contactor is connected in series with the coil winding of the first contactor and then connected to the neutral wire. The normally open switch of the first contactor and the normally open switch of the fourth contactor are connected in parallel.

6. The fire pump start-up control system according to claim 4, characterized in that: The delay duration of the timer corresponding to each of the fire pumps is different.

7. The fire pump start-up control system according to claim 3, characterized in that: The system start unit uses a start button, and the system stop unit uses a stop button. The start button and stop button are connected to the two signal input terminals of the controller.

8. The fire pump start-up control system according to claim 3, characterized in that: The controller is connected to a display screen for outputting the current curve waveform.

9. The fire pump start-up control system according to claim 2, characterized in that: The main circuit also includes a DC power supply, the input terminal group of which is connected to the output terminal of the main circuit breaker, and the output terminal group of which is connected to the power input terminal group of the controller in the secondary control circuit.

10. The fire pump start-up control system according to claim 9, characterized in that: The main circuit also includes a current transmitter, whose power input terminal group is connected to the output terminal group of the DC power supply. The signal input terminal of the current transmitter is used to sample any one phase of the three-phase power output by the boost converter. The signal output terminal of the current transmitter is connected to the controller in the secondary control circuit.

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