1. Application environment and precautions of frequency converter
1.1 working environment of inverter
(1) The working environment temperature is – 10 ℃ ~ + 40 ℃. The change of working environment should not be greater than ± 5 ℃ / h.
(2) Relative humidity: the maximum relative humidity of the air shall not exceed 90%, and the change rate of the relative humidity per hour shall not exceed 5%, and there shall be no condensation.
(3) The working site shall be free from conductive or blasting dust, gas or steam that corrodes metal or damages insulation.
(4) Allowable oscillation conditions of frequency converter equipment address:
The oscillation frequency is 10-150 Hz, and the oscillation acceleration is not greater than 5 m / S2. When the frequency converter may resonate due to the equipment base oscillation, vibration reduction method should be selected to avoid the resonance frequency.
(5) Communication input power
The voltage should not exceed ± 20%.
If the frequency is not determined, it should not exceed ± 2%, and the frequency change should not exceed ± 1% per second.
Unbalance degree of three-phase voltage: negative sequence weight does not exceed 5% of positive sequence weight;
Power harmonic component: the root mean square value of voltage relative harmonic content does not exceed 10%.
(6) Altitude: no more than 1000m.
(1) Non professional personnel should not open the cover and open the cabinet door to use or check;
(2) The voltage withstand test has been done before the inverter leaves the factory, so the user can’t do it and there is no need to carry out the withstand voltage test on the inverter;
(3) Large capacitors for improving power factor should not be connected to the motor in parallel;
(4) The shell is firmly grounded;
(5) Do not change the three-phase input to two-phase input, otherwise it will appear phase loss maintenance;
(6) When working at low frequency, we should consider the effect of motor’s own fan and smooth effect, and when working at high frequency, we should consider the acceptance of bearing before adjusting.
These theories describe the most fundamental rules of inverter equipment. We should deepen our understanding of these rules.
2. Preparation before equipment
In order to equip a frequency converter to make it work normally and reach the skills and skills request, in addition to satisfying the above-mentioned basic rules, we should also pay attention to the following points:
(1) Before the equipment, it is necessary to understand and grasp the production skills and skill request, understand its load status, and understand the effect and orientation of frequency converter in the system. It is to ask for energy saving, or to improve production skills, or both. In some fields, there is no energy-saving space, and it is not stable to implore the frequency converter to save energy.
(2) From the electrical aspect, the load of frequency converter is mainly the motor. Therefore, before the equipment, it is necessary to have a comparative understanding of the field motor, including additional voltage, additional current, motor pole number, additional power, etc. the frequency converter of the equipment is necessary to match with it. In some special occasions, such as heavy load, altitude over 1000m (i.e., across the standard altitude), coal mine The frequency converter of trekking machine is one or two power levels higher than the load motor. Generally, the power level of the frequency converter is not allowed to be lower than that of the load motor, so as to avoid the frequency converter working overload without moving or overload maintenance, which constitutes unnecessary trouble.
(3) It is necessary to check the electrical insulation equipment of the motor. The motor with poor insulation cannot be equipped with frequency converter. Although the frequency converter is equipped with short circuit maintenance, the instantaneous grounding may also cause damage to some frequency converters.
(4) Before the equipment, carefully read the operation instructions of frequency converter, contact the on-site skills, which parameters should be set, and how to set the parameters, etc., to master them skillfully.
(5) For some occasions, the external demands for active control and the need for subordinate accessories, such as pressure gauge, sensor, pressure transmitter and some supporting equipment for water supply, such as PID controller, temperature controller, time clock, etc., and some also require remote control equipment and be skillful. In order to be able to activate the equipment, commissioning in place.
(6) Wiring should be carried out in strict accordance with the operation specification of frequency converter, including the main line and control line. Some conditions can only be higher than the specification of the specification in the specification, but not lower than. In the local area where crimping is required, the crimping shall be strictly carried out according to the request, and the specifications and skills shall conform to the specifications.
(7) Under the condition of disorderly modern industrial control, it is necessary to consider the electromagnetic compatibility, the disturbance and anti disturbance of frequency converter, and to install electromagnetic filtering equipment when necessary. In some cases, the motor interval converter may be far away, so it is necessary to consider adding output reactor and filter.
(8) For potential energy load, such as mine main shaft winch, trekking machine and elevator, due to the regenerative power generation situation, it is necessary to consider installing brake unit and matching braking resistor to avoid over-voltage maintenance or damage of frequency converter.
The above questions are all what we should understand and grasp before the equipment frequency converter. If we do not understand these contents, it may constitute that the equipment of the frequency converter is not smooth or the debugging is not successful at all, and the equipment is damaged or can not be used normally. This is what we should bear in mind.