Correct choice of valve electric device to prevent overload of the phenomenon of

 Correct choice of valve electric device to prevent overload of the phenomenon of



Valve electric device is programmed to achieve the valve, self-control and remote control can not be a lack of equipment, the process of its movement can be stroke, torque, or to control the size of the axial thrust. As the valve electric device operating characteristics and utilization depend on the type of valves, fittings and valves regulate the work or equipment at the location on the pipeline, therefore, correct choice of valve electric device, to prevent overload phenomenon (the work is delegated Moments higher than the control torque), is essential.







     Typically, the correct choice of valve electric device based on the following:



  



     Operation torque torque operation is to choose the most important parameters of valve electric device, electric device output torque valve operation should be the greatest moment of 1.2 ~ 1.5 times.



     Operation Thrust host structure of the valve electric device, there are two: one is not configured thrust plate, direct output torque; the other is to configure thrust plate, the output torque of the stem nut through the thrust disk is converted to the output thrust.



     Output shaft rotational number of laps valve electric actuator output shaft rotation the number of laps and the valve nominal diameter, stem pitch, thread the first few related, according to M = H / ZS calculated (M for the electrical installations should meet the total the number of rotating ring, H is the valve opening height, S for stem transmission thread pitch, Z for the valve stem thread first few).



     Stem diameter and rotational ming for multi-pole valve, if the electrical device allows the maximum stem diameter of the valve stem can not be dispensed, it can not be assembled into electric valve. Therefore, the electrical device hollow output shaft diameter must be greater than specified under the valve stem diameter. On the part of the rotary valves, as well as multi-turn valves in the dark bar valves, although without considering the adoption of stem diameter, but should also take full account of the matching stem diameter and keyway size, so that work can be assembled .



     Valves open and close the output speed if the speed too quickly, is easy to produce water hammer phenomenon. Should therefore be used under different conditions, choosing the appropriate hoist speed



     Valve electric device has its own special requirements that must be able to limit the torque or axial force. Valve Electric installations are usually limited torque Couplings. When the electrical device specification is established, its control torque also determined. Usually in a pre-determined period of time to run the motor is not overloaded. However, if the following conditions it may lead to overload: First, the supply voltage is low, are not required torque, the motor stops rotating; second is wrong it is set torque limit agencies, so that the torque is greater than stop , resulting in too big produces a continuous torque, the motor stops rotating; third intermittent use, the heat generated savings of more than the permitted temperature rise of the motor; Fourth, for some reason, body torque limit circuit failure, so that torque too large; 5 is to use the ambient temperature is too high, the relative decline in the motor heat capacity.



     In the past to protect the motor way is to use fuses, overcurrent relays, thermal relays, thermostats, etc. However, these methods have their own advantages and disadvantages. This change of the electrical device load device, absolutely reliable protection method is not. Therefore, we must adopt various combinations, be summed up in two ways: First, changes in the input current to the motor to judge; second heat of the motor itself, to judge. These two methods, regardless of the kind of motor thermal capacity must take into account the given time margin.



     Typically, the basic overload protection methods are: continuous operation of motor jog operation, or overload protection, using a thermostat; right motor locked rotor protection, thermal relay; pairs of short-circuit accident, following the use of fuse or over-current appliances.



  



The distribution on the valve market are based mainly on the construction of the project, the largest user of the valve is the petrochemical industry, power sector, metallurgy sector, the chemical industry and urban construction departments. Petrochemical industry major applications API standard gate valve, globe valve and check valves; electricity sector, mainly in power stations using high-temperature pressure valve, globe valve, check valve and safety valve, and part of the low-pressure water supply and drainage valve butterfly valve, gate valve; the chemical industry mainly uses stainless steel valve, globe valve, check valve; metallurgical industry mainly uses low-voltage large-diameter butterfly valve, oxygen valve and oxygen valves; urban construction department used mainly low-pressure valve, such as urban water mainly uses large-diameter brake pipe valve, the main floor, blending the building with the center line butterfly valve, urban heating primarily metal sealing butterfly valve; oil pipeline used mainly flat valve and ball valve; the pharmaceutical industry mainly uses stainless steel ball valve; the food industry mainly uses stainless steel ball valve and so on. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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