On the selection of electric actuator and its deve

Talking about the type selection and development trend of electric actuator (Part 2)

1 anti dripping vertical dripping has no harmful effect

2 15 when the anti dripping equipment is within 15 angles from the vertical line, the vertical dripping has no harmful effect

3 there is no harmful effect when the anti drenching water is within 60 degrees from the vertical line

4 prevent splashing. Splashing in any direction has no harmful effect

5 anti water spray has no harmful effect on flushing in any direction

6 prevent the water entering the shell from reaching harmful effects in case of strong waves or strong water spray

7 prevent immersion. After immersion in water with specified pressure for a specified time, the amount of water entering the shell will not reach harmful effects

8 can dive for a long time according to the conditions specified by the manufacturer, and its technical conditions are specified by the manufacturer

2. Explosion proof grade

in places where explosive gas, steam, liquid and the principle of imitation wood gem layer are the same, combustible dust, etc. may cause fire or explosion hazards, it is necessary to put forward explosion-proof requirements for electric actuators, and choose explosion-proof types and categories according to different application areas. The explosion-proof grade can be indicated by the explosion-proof mark ex and the explosion-proof content (refer to explosion proof electrical equipment for explosive atmospheres GB)

the contents of explosion-proof signs include: explosion-proof type + equipment category + (gas group) + temperature group

A) explosion proof type: according to the explosion-proof measures taken, it can be divided into intrinsically safe type, explosion-proof type, increased safety type, positive pressure type, pouring sealing type, sand filling type, etc. Their identification is shown in Table 3 below

Table III. explosion proof form and mark

explosion proof type explosion proof type mark explosion proof type explosion proof type mark

intrinsically safe exi explosion proof type Exd

sand filled e x Q increased safety type exe

pouring d) determination results and production date of this batch of products sealed e x m positive pressure type exp

b) equipment category:

Table IV. equipment category

class I underground electrical equipment for coal mines

class II electrical equipment for explosive gas environment other than coal mine

class II flameproof Exd and intrinsically safe exi electrical equipment are further divided into IIA, IIB, and IIC according to their maximum test safety gap or minimum ignition current ratio applicable to explosive gas mixtures. The relationship between others is shown in Table 5:

table 5 Gas group

Gas Group maximum test safety gap MESG (mm) minimum ignition current ratio MICR

IIA MESG 0.9 MICR> 0.8

at the same time

IIB 0.9> MESG> 0.5 0.8 MICR 0.45

IIC 0.5 MESG 0.45> MICR

C) temperature category:

electrical equipment is divided into T1 ~ T6 groups according to its maximum surface temperature, so that the corresponding T1 ~ T6 groups.The maximum surface temperature of the electrical equipment of group A shall not exceed the allowable value of the corresponding temperature group. The relationship between temperature group, equipment surface temperature and ignition temperature of combustible gas or steam is shown in Table 6:

Table 6 Temperature group

temperature level maximum surface temperature of equipment t ignition temperature of combustible substances

T1 450 ℃ t 450 ℃

T2 300 ℃ 450 ℃ T> 300 ℃

T3 200 ℃ 300 ℃ t> 200 ℃

T4 135 ℃ 200 ℃ T> 135 ℃

T5 100 ℃ 135 ℃ T> 100 ℃

T6 85 ℃ 100 ℃ T> 85 ℃