1. The voltage level is consistent with the control motor.
2. Select the type of inverter according to the load characteristics of the controlled equipment. For constant torque load, it is best to use the inverter with wide driving torque limit.
There are three types of loads: constant torque loads, fans, pump loads, and constant power loads.
3, the working environment
a is required to be -10 ° C ~ 50 ° C, preferably controlled below 40 ° C.
b If the work site is dusty, high temperature, high humidity, and contains corrosive gases, it is necessary to take appropriate protective measures.
Selection of explosion-proof frequency converter
1. Explosion-proof electrical equipment related knowledge
(1) Hazardous places:
According to the provisions of GB3836.14-2000 "Electrical Equipment for Explosive Gas Environments, Part 14: Classification of Hazardous Locations", dangerous places can be divided into Zone 0, Zone 1, Zone 2.
(a) Zone 0: A place where an explosive gas atmosphere continuously appears or exists for a long time.
(b) Zone 1: A location where an explosive atmosphere may occur during normal operation.
(c) Zone 2: In normal operation, an explosive atmosphere is unlikely to occur, and if it occurs, it is occasionally occurring and is only a short-lived place.
2. category:
The types of electrical equipment are related to the environment in which they are used. There are two main categories: - Class I: Electrical equipment for coal mines. - Class II: Other explosive atmospheres other than coal mines. Class II explosion-proof "d" electrical equipment according to the maximum test safety clearance, intrinsically safe "i" electrical equipment is divided into IIA, IIB, IIC according to the minimum ignition current (IIB class is the most widely used, only hydrogen The IIC class is required for acetylene sites, see Table 3).
3. Maximum surface temperature:
When the electrical equipment is operated under the most adverse conditions within the allowable range, it can cause the highest temperature of any part or surface ignited by the surrounding explosive environment.
4. Ignition temperature:
The lowest temperature at which a flammable gas or mixture of vapor and air is ignited by a hot surface under specified conditions (see Table 1).
5. Temperature group:
The group of electrical equipment divided by its highest surface temperature (see Table 1). Table 1 Relationship between temperature group, surface temperature and ignition temperature Temperature group of electrical equipment Maximum surface temperature of electrical equipment Ignition temperature of gas or vapor T1 450 °C >450 °C T2 300 °C >300 °C T3 200 °C >200°C T4 135°C >135°C T5 100°C >100°C T6 85°C >85°C
6. Dust explosion-proof dangerous places:
According to the frequency and duration of the explosive or flammable dust environment, the dust explosion hazard is divided into: Zone 21: The dust cloud or dust layer and air mixed with or appearing during normal processing, treatment or cleaning. The area where the explosive concentration is reached. Zone 22: A site not classified as Zone 21, but under abnormal conditions, a dust cloud or a layer where the dust layer and air are mixed to reach the explosive concentration can be found in the site.
7. The relationship between dust temperature group, ignition temperature, and maximum surface temperature (Table 2).
Table 2 Temperature group ignition temperature T Maximum surface temperature No overload There is an approved overload T11 T>270°C 215°C 190°C T12 <200°CT≤270°C 160°C 145°C T13 <150°CT≤200°C 120°C 110 °C
8. Examples of flammable gases allowed in the use environment:
Table 3 Temperature group category T1 T2 T3 T4 IIA, IIB, IIC methane, ethane, propane, styrene, benzene, toluene, xylene, acetone, carbon monoxide, phenol, cresol, dichloroethylene, chlorobenzene, ammonia, Propyne, acrylonitrile, hydrogen cyanide, coke oven gas, hydrogen and other butane, cyclopentane, propylene, ethylbenzene, cumene, methanol, ethanol, propanol, butanol, cyclohexanone, methyl formate , ethyl acetate, dichloroethane, vinyl chloride, methylamine, ethylene, acetylene and other pentane, hexane, cyclohexane, turpentine, naphtha, petroleum, kerosene, fuel oil, gasoline, pentanol, hexanol Ethyl methyl ether such as chlorobutane, dimethyl ether or crotonaldehyde, acetaldehyde, dibutyl ether and diethyl ether
Note: This table is quoted from the contents of Appendix B of GB3836.1-2000 "Electrical Equipment for Explosive Gas Atmospheres Part 1: General Requirements".
Basic physical principles and definitions of explosion protection
When a flammable object chemically interacts with oxygen in the event of a sudden high temperature, an explosion occurs. There are many types of flammable objects, including gases, steam, mist and dust. The three necessary conditions that cause a fire or explosion are:
a combustible concentration of combustibles
b Oxygen (in the air)
c ignition source
Explosion-proof form of explosion-proof electrical appliances
Flameproof type (a type of explosion-proof type, indicated by the letter "d")
Electrical equipment with a flameproof enclosure that withstands the explosive pressure of the internal explosive gas mixture and prevents the internal explosion from propagating to the explosive enclosure surrounding the enclosure.
Increased safety type (a type of explosion-proof type, indicated by the letter "e")
In normal operating conditions, where no arcing, sparking or high temperature equipment may ignite the explosive mixture, measures are taken to increase the degree of safety to avoid electrical equipment that exhibits these phenomena under normal and approved overload conditions.
Wood safety type (a type of explosion-proof type, indicated by the letter "i")
Emissions and thermal effects that occur during normal operation or specified fault conditions or short circuits do not ignite the circuit equipment of the explosive mixture.
Positive pressure type (a type of explosion-proof type, indicated by the letter "p")
An electrical device with a positive pressure enclosure that maintains the pressure of the internal shielding gas above the pressure of the surrounding explosive environment and prevents the external mixture from entering the enclosure.
Oil-filled type (a type of explosion-proof type, indicated by the letter "o")
All or part of the components are immersed in the oil so that the equipment cannot be electrically connected to an explosive mixture above the fuel surface or outside the casing.
Sand-filled type (a type of explosion-proof type, indicated by the letter "q")
The sand material is filled into the outer casing so that under the specified conditions of use, the arc generated in the casing, the propagating flame, the outer wall of the casing or the surface of the sand material cannot overheat the electrical equipment of the surrounding explosive mixture.
Non-sparking type (a type of explosion-proof type, indicated by the letter "n")
Under normal operating conditions, the surrounding explosive mixture will not ignite and generally does not have electrical equipment that ignites.
Molded type (a type of explosion-proof type, indicated by the letter "m")
Part of the arc, spark or high temperature that may ignite the explosive mixture is encapsulated in the potting agent so that it does not ignite the surrounding explosive mixture.
Airtight type (a type of explosion-proof type, indicated by the letter "h")
A sealed enclosure that is melted, extruded, or glued to prevent gas from entering the shell outside the shell.