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电动阀门装置应注意的问题

2013-1-15 12:03:53      点击:
操作力矩:操作力矩是选择阀门电动装置的最主要参数,电动装置输出力矩应为阀门操作最大力矩的1.2~1.5倍。操作推力:阀门电动装置的主机结构有两种:一种是不配置推力盘,直接输出力矩;另一种是配置推力盘,输出力矩通过推力盘中的阀杆螺母转换为输出推力。输出轴转动圈数:阀门电动装置输出轴转动圈数的多少与阀门的公称通径、阀杆螺距、螺纹头数有关,要按M=H/ZS计算(M为电动装置应满足的总转动圈数,H为阀门开启高度,S为阀杆传动螺纹螺距,Z为阀杆螺纹头数)。 阀杆直径:对多回转类明杆阀门,如果电动装置允许通过的最大阀杆直径不能通过所配阀门的阀杆,便不能组装成电动阀门。因此,电动装置空心输出轴的内径必须大于明杆阀门的阀杆外径。对部分回转阀门以及多回转阀门中的暗杆阀门,虽不用考虑阀杆直径的通过问题,但在选配时亦应充分考虑阀杆直径与键槽的尺寸,使组装后能正常工作。输出转速:阀门的启闭速度若过快,易产生水击现象。因此,应根据不同使用条件,选择恰当的启闭速度。阀门电动装置有其特殊要求,即必须能够限定转矩或轴向力。通常阀门电动装置采用限制转矩的连轴器。当电动装置规格确定之后,其控制转矩也就确定了。一般在预先确定的时间内运行,电机不会超负荷。但如出现下列情况便可能导致超负荷:一是电源电压低,得不到所需的转矩,使电机停止转动;二是错误地调定转矩限制机构,使其大于停止的转矩,造成连续产生过大转矩,使电机停止转动;三是断续使用,产生的热量积蓄,超过了电机的允许温升值;四是因某种原因转矩限制机构电路发生故障,使转矩过大;五是使用环境温度过高,相对使电机热容量下降。过去对电机进行保护的办法是使用熔断器、过流继电器、热继电器、恒温器等,但这些办法各有利弊。对电动装置这种变负荷设备,绝对可靠的保护办法是没有的。因此,必须采取各种组合方式,归纳起来有两种:一是对电机输入电流的增减进行判断;二是对电机本身发热情况进行判断。这两种方式,无论那种都要考虑电机热容量给定的时间余量通常,过负荷的基本保护方法是:对电机连续运转或点动操作的过负荷保护,采用恒温器;对电机堵转的保护,采用热继电器;对短路事故,采用熔断器或过流继电器。

 

 

译文:
Operating torque: torque operation is to select the most important parameters of valve actuators, electric actuator output torque maximum torque valve operation should be 1.2 ~ 1.5 times. Operating Thrust: electric valve actuators of the host structure, there are two: one is not configured thrust plate, the direct output torque; the other is the thrust plate configuration, the output torque of the valve stem nut through the thrust plate is converted to output thrust. Output shaft revolutions: electric valve actuators output shaft revolutions and the number of nominal diameter valve stem pitch, the first few threads, according to M = H / ZS calculated (M is the electric equipment should meet The total number of revolutions, H is the valve opening height, S is the stem transmission thread pitch, Z is the number of stem thread first). Stem diameter: the next shot on the multi-turn type valves, electrical equipment if the maximum allowed by the stem diameter can not be dispensed through the valve stem, the valve can not be assembled into electric. Therefore, the electric device inside diameter of the hollow output shaft must be greater than the next shot of the valve stem diameter. On the part of the rotary valve and rotary valve valve rod in the dark, although not considered by the stem diameter, but should also take full account of the matching stem diameter and keyway sizes, so that after assembly to work . Output speed: If the valve opening and closing speed too fast, easy to produce water hammer phenomenon. Therefore, according to the different conditions of use, choose the appropriate opening and closing speed. Electric valve actuators have special requirements that must be able to limit the torque or axial force. Usually limit the use of electric valve actuators torque coupling. When the electric device specifications determined, the control torque is also determined. Generally operate within a predetermined time, the motor will not overload. However, if the following conditions may lead to overload: First, the supply voltage is low, not the required torque, the motor stops rotating; the second is wrong it is set torque limit institutions to stop the torque is greater than , resulting in continuous excessive torque, the motor stops rotating; Third, intermittent use, savings generated by the heat, more than the allowable temperature rise of the motor; Fourth, institutions for some reason the torque limit circuit fault, the torque is too large; Fifth, the ambient temperature is too high, the relative decline in the motor thermal capacity. Past the motor protection is to use fuse, overcurrent relays, thermal relays, thermostats, etc., but these approaches have advantages and disadvantages. This variable load on the electric equipment installation, absolutely reliable protection method is not. Therefore, we must take a variety of combinations, summed up in two ways: First, changes in the motor input current to judge; second heat of the motor itself to judge. These two methods, regardless of the kind must take into account the motor thermal capacity margin is usually given time, the basic overload protection methods are: continuous operation of the motor jog operation or overload protection, the use of a thermostat; of Stall protection, thermal relay; of a short circuit, the use of fuses or overcurrent relays.