Key words: transducer transducer calorific value
In daily work, inverter selection should pay attention to what matters? First of all we want to know the inverter is not in any case to normal use, so the user need to load, environmental requirements and converter have more understanding. Divided into seven places of attention:
1, long-term low-speed moving, due to the high calorific value of the motor, the cooling capacity of the fan is reduced, it must be used to increase the speed reduction ratio or switch to the 6 motor, the motor running at a higher frequency.
2, the installation site must conform to the standards of inverter environmental requirements, otherwise easily lead to failure or shorten the service life; between inverter and motor driving distance is generally not more than 50 meters, if the longer distance is required to reduce the carrier frequency or increase the output options to the normal operation of reactor.
3, load type and frequency converter selection:
Motor driven load is not the same, the requirements of the inverter is not the same.
4, fan and pump load is the most common: on the inverter for the most simple, as long as the inverter capacity is equal to the capacity of the motor can be (air compressor, deep water pump, mud pump, the rapid change of the need to increase the capacity of the music fountain).
5, crane load: this type of load is characterized by a great impact on the start, so that the inverter has a certain margin. At the same time, the weight of the elbow, there will be energy feedback, so use the brake unit or the use of common bus mode.
6, uneven load: some load is sometimes light, sometimes heavy, at this time should be in accordance with the situation of heavy load to select the inverter capacity, such as rolling machinery, crushing machinery, mixer, etc..
7, large inertia load: such as centrifuges, presses, cement plant rotary kiln, such a large load inertia, so it may start oscillation, motor deceleration when there is energy feedback. It should be used to increase the capacity of the inverter to speed up the start to avoid oscillation. With the brake unit to eliminate feedback power.
Second, the use of eight inverter notes
1, vibration and shock. Equipped with inverter control cabinet is subject to mechanical vibration and shock, will cause poor electrical contact. At this time, in addition to improving the mechanical strength of the control cabinet, away from the vibration source and the impact of the source, but also the use of anti seismic rubber pad fixed outside the control cabinet and the electromagnetic switch, such as the vibration of the components. Check and maintain the equipment after running for some time.
2, electrical environment, physical environment, environmental temperature. When the temperature is too high and the temperature changes, the frequency converter is easy to appear condensation phenomenon, the insulation performance will be greatly reduced, and may even lead to short-circuit accident. If necessary, add desiccant and heater in the box.
3, working temperature. The internal electronic components of high power, extremely easy to be influenced by the working temperature of the product, the general requirements for 0 ~ 55 degrees, but in order to ensure the safe and reliable work, use should be considered under the best control in 40 DEG C. In the control box, the installation of the inverter should strictly comply with the installation requirements of the product specification, the heating element or the heating element is not allowed to close to the bottom of the transducer.
4, to prevent excessive input voltage. The input end of the inverter power supply often has over-voltage protection. However, if the input voltage is high, the input end of the inverter will be damaged. Therefore, in the actual application, to verify the inverter input voltage, single phase or three phase inverter and the use of rated voltage. In particular, the power supply voltage is not stable when there is a voltage regulator, otherwise it will cause serious consequences.
5, corrosive gas. The use of the environment if the concentration of corrosive gas, not only the corrosion of lead components such as printed circuit boards but also accelerate the aging of plastic devices to reduce the insulation performance, in this case, the control box made of closed structure, and ventilation
6, to prevent electromagnetic interference. Inverter in the work due to rectification and inverter, resulting in a lot of interference around the electromagnetic wave, these high-frequency electromagnetic waves on the instrument, the instrument has some interference. Therefore, the instrument and the electronic system in the cabinet, should choose the metal shell, to shield the inverter to the instrument interference. All the components should be grounded and reliable, in addition, between the various electrical components, instruments and instruments should be used to connect the control cable shielding and shield should be grounded. If the electromagnetic interference is not handled well, the whole system will be unable to work.
7 correct grounding inverter control system is an important means to improve the sensitivity and noise suppression ability, inverter ground terminal E (G) grounding resistance as small as possible, the grounding conductor cross-sectional area should not be less than 2mm2, the length should be controlled within 20m. The grounding of the frequency converter must be separated from the grounding point of the power equipment. Shielding layer of the signal input line, connected to E (G), and the other end is not connected to the end, otherwise it will cause the signal fluctuation, make the system oscillation more than. The electrical connection between the frequency converter and the control cabinet, if the actual installation is difficult, the use of copper core wire.
8 in the frequency converter, generally equipped with lightning absorption network, mainly to prevent the sudden lightning intrusion, so that the inverter damage. However, in practical work, especially in the case of overhead power lines, the frequency converter can not meet the requirements. In the lightning activity areas, this problem is particularly important, if the power supply is overhead line into, in line arrester installed special frequency (optional), or according to the specifications in the distance from the pre buried steel converter 20m special grounding protection. If the power supply is introduced into the cable Do a good job in the control room lightning protection system, in order to prevent the lightning into the destruction of equipment. Practice shows that the problem can be solved effectively.