How Fire Pump Startup Mode Will Affect the Reliability of Water Supply Equipment

We all know that in the event of a fire in a high-rise building, it is necessary to build a self-rescue system for each high-rise building based on a bolting system or an automatic sprinkler system. In other words, it is very important that high-rise buildings mainly rely on their own building. Here, the fire-fighting pump can be set up to complete the fire. To this end today we talk about a little fire pump startup advice.

First of all, we should be clear that the fire water supply equipment is composed of fire pump units, pipelines, valves, electric control cabinets, and a meter. There are many factors influencing the reliability of fire-fighting water supply equipment. From the perspective of mathematics, the analysis of probabilities leads to the conclusion that reliability is a commonly used method. This paper only uses the starting mode of fire pump and the application of relevant new technologies. To discuss the reliability of water supply equipment.

at least to start direct way <br> <br> direct line start-up mode using the device, are passive devices, this start-up mode to start the fire pumps are the most rapid and maximum starting current on the grid transformer capacity requirements are also the largest, consider The start-up characteristics of the pump motor used so far are better, and because the pump is a square rate load, it can also be regarded as a light-load start. For a low-voltage motor, the power of a single motor can be considered as 90 kW, and for a high-voltage motor (6 kV or 10 kV). Its power range can reach several megawatts. When the fire pump overload and over-current condition occurs, it is based on the type protection of the thermal magnetic release device, but when its thermal relay is in operation, it will “alarm only and will not trip”. This is the simplest, most economical and most reliable way to start.

2, Star - delta start way <br> <br> Star - delta starting line way more direct way to start a little more complicated, but also are passive devices, usually start to finish in the 60s, its start-up current more direct way to start small . Therefore, it can be considered that the power of a single motor can be set to 110kW, and this line is only used for low-voltage motors. When the fire pump overload and over-current condition occurs, it is based on the type protection of the thermal magnetic release device, but when its thermal relay is in operation, it will “alarm only and will not trip”. Because the circuit is slightly more complicated, the probability of failure is higher than the former.

3, autotransformers
<br> <br> start mode starts from the mode coupling transformer circuit complexity than the first two, are also passive devices, start time may be generally completed within 90s, which is the starting current smaller than the first two Therefore, the power of a single motor in this mode can reach around 160kW. This line is only used for low-voltage motors. When the fire pump overload and over-current condition occurs, it is based on the type protection of the thermal magnetic release device. However, when its thermal relay is in operation, it will “alarm only, and it will not fail to brake.” Since the line is also more complex than the previous two, the fault will occur. The probability is higher than the first two.

4. The KB0 startup mode KB0 startup mode is also a passive startup mode. It integrates the main functions of separate components such as circuit breakers, contactors, overload relays, and isolation switches, and can integrate multiple signals to achieve control and protection characteristics. Self-combination within the product. It has the advantages of small size, high short-circuit breaking performance index, long electrical and mechanical life, high operational reliability, safe and convenient use, energy saving, and material saving. However, because the device's rated current rating can only reach 125A and there is no high voltage product, it can only be applied to low-power low-pressure fire pumps and is limited. In addition, it should be noted that when selecting a type, be sure to use fire-fighting products. Because, when the fire pump overload, over-current, the device "does not switch off, only alarm", in line with the fire pump control protection requirements. This method, when applied to low-power fire pumps, has a significant improvement in reliability and is superior to the previous methods. At the same time, the cost will be higher.

5. The soft starter startup mode RQ device is a soft starter. This is an active startup method, and the circuit is more complex than the previous ones. The biggest advantage of this method is that there is no start-up current. Its start-up time can be conveniently set according to the pump motor power from 0 to 3600s. Therefore, the power range of a single motor can reach hundreds of kilowatts. For the reason of the device, this method is mostly used for low voltage. Motors (currently reported on the application of high-pressure pumps) are also well suited for EPS power supplies. Because its protection is electronic, fire pump overload, overcurrent, power supply undervoltage, lack of equal causes will immediately enter the "tripping" protection, turn off the output, which is the characteristics of active devices. In the event of a fire, the fire pump will immediately stop operating if the fire pump is overloaded or the power supply experiences overpressure, underpressure, etc. Therefore, its reliability is slightly worse than the previous methods.

6, when the inverter startup mode <br> <br> applied when the high-pressure pump needs to configure the input and output transformers. This is an active start method, and the line and soft starter methods are even more complicated. It also has no start-up current, and its start-up time can be easily set. The single-motor power and motor voltage range can reach several megawatts and 10kV. Also very suitable for EPS power supply. Because of its complicated circuit, especially the drive's activeness, its reliability is worse than the previous ones.

To sum up, the soft starter and the frequency converter are both active and passive. The other methods are passive. How to evaluate the reliability of the active mode?

Let's first look at the status of fire pump applications:

Both soft starters and frequency converters are imported products and have been widely used in China since the mid-1980s. However, we have noticed a phenomenon that this content is not covered in the NFPA standard and FM's certified products, and there is no report on the use of soft starters and inverters as fire pump startup methods and articles. This cannot be seen as their negligence. Because soft-starters and frequency converters are widely used in pumps used for life and production in equipment imported from many countries, such as Europe and the United States. This can be understood as a way they proceed from the reliability of fire-fighting equipment and is not promoted. However, the situation in our country is completely different. The active starting mode is widely used in the start-up of fire pumps. At present, the quality of soft starters and frequency converters used in our country is uneven, brand quality is also uneven, and the level of users is different. The understanding and understanding between design and application parties are quite different. For example, in the overload protection mode of the fire pump, the active and passive methods are quite different. When in the passive mode, its thermal magnetic protection (thermal relay) is overloaded and only alarms the pump. However, in the active mode, its accurate electronic protection immediately shuts down the output of the soft starter or the inverter after the overload and stops the pump. At this time, if a fire incident occurs, how to start the fire pump to provide the water source, thus completing Fire fighting?

Liang Bang believes that it is not advisable to use active methods for the selection of fire pump start-up methods. Passive methods should be adopted. The direct start method can meet the requirements of most buildings for the capacity of fire water supply equipment, so it should be recommended first. At present, it is time to standardize the way of starting the fire pump (at present, there is not yet a norm in China). Otherwise, it is undoubtedly a management loophole that emphasizes the importance of fire safety today. The instability of building fire protection.

Finally, let's talk about what to do if the fire pump fails to start when the fire control pump's startup control circuit (secondary circuit) fails. The following describes a fire-fighting water supply equipment control device with an emergency start-up fire pump mechanism.

The device is characterized by the connection structure of a main circuit composed of dual power supply conversion lines and low-voltage electrical appliances and the structure of a voltmeter, an ammeter, a plurality of indicator lights and a button on the front panel of the cabinet, including an operating handle, a latch, and a The linkage lever driven by the operating handle, the return spring on the linkage rod, the rotary switch driven by the linkage rod, the crossbar driven by the interlocking rod, and the adjustable short rod driven by the crossbar comprise a fire emergency. The manual mechanism to start the fire pump. The rotary switch driven by the interlocking lever is turned off after the operating handle rotates 90° counterclockwise. The short rod is made of insulating material, and it is threaded and has two nuts to adjust and fasten the short rod. The standard of the short rod is to make it away from the main contactor in the main circuit in the short rod from the handle. The driving force at the time of pushing in may make all the contacts of the main contactor solid and cannot produce a virtual connection. The latch is installed on the side beam of the cabinet, and it is the moving shaft of the linkage rod. After the handle is rotated 90° counterclockwise and pressed, it will jam the linkage rod, so that the linkage short rod can continue. Press on the main contactor. Then, when the handle rotates clockwise, the return spring on the interlock lever will return it to the position. The crossbar is an I-beam structure. One end of the crossbar is fixed on the other side beam of the cabinet body in the form of a shaft. With this axis, it can move in parallel; the other end is moved by parallel movement of the linkage lever. This parallel movement causes the short rod to press or discharge the main contactor.

When a fire incident occurs, if the circuit of the fire pump control cabinet fails to allow the fire pump to start, the authorized person can immediately operate the handle, rotate it counterclockwise by 90°, and press it with proper force. At this point, the main contactor of the main circuit is forced down, that is, the motor feed power of the fire pump is switched on. In this way, the pump is forcibly started (instead of the start-up procedure according to the original circuit). The reason why the counterclockwise rotation is performed first is to operate the rotary switch to first disconnect the power supply of the secondary control circuit in the control cabinet. After the fire incident ends, the authorized person only needs to turn the handle clockwise, and it will be automatically reset to the initial state by the return spring.

Author: Yong Jia Liangbang pump manufacturers

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