【 Weak current College 】 transducer principle control chart design---Power By 【 China power house network 】

A first confirmation inverter installation environment;

1. working temperature. Inverter is high-power electronics inside, vulnerable to the effects of working temperature, General requirements for 0 ~ 55 ° c, but in order to ensure the security, reliability, you should consider when making the best control in 40 ° c below. In the control box, the inverter should normally be installed on the box in the upper part, and in strict compliance with the product specification of installation requirements, do not allow the heating element or component easily heat close to the bottom of the installation of frequency converters.

2. the ambient temperature. The temperature is too high and larger temperature changes, inverter internal condensation phenomenon occurred, its insulation properties will be greatly reduced, or even possible short-circuit accident. When necessary, must be in the box to increase desiccant and heater. In water treatment, water vapour is heavier in General, if the temperature changes, this issue will be more prominent.

3. corrosive gases. Use the environment if corrosive gas concentration, not only will the lead corrosion components, such as printed circuit board, and will accelerate ageing of plastic components, lowering the insulating performance.

4. vibration and shock. Equipped with Inverter control cabinets subject to mechanical vibration and shock, causing poor electrical contact. Huaian thermoelectric appears such a problem. Then in addition to improving control cabinet of mechanical strength, away from the vibration source and impact source, you should use the seismic rubber pad fixed control cabinet outside and inside the solenoid switch components such as vibration. Equipment run time, you should check and maintenance.

5. electromagnetic interference. Inverter in work due to the commutation and frequency, surrounded by a lot of interference electromagnetic wave, these high-frequency electromagneticwave on the instrument, apparatus in the vicinity there are disturbed. Therefore, the Cabinet Interior instrument and electronic systems, you should choose the metal casing, shielding disturbance frequency converter on the instrument. All components shall be reliable grounding, in addition, various electrical components, instruments and meters between the wiring should use shield control cable, and the screen should be ground. If treatment is not good electromagnetic interference, tend to make the whole system does not work, resulting in malfunction or damage to the control unit.

2 inverter and motor distance cable and wiring methods;

1. the inverter and motor short distance should, as far as possible. This reduces cable to ground capacitor, reducing interference emission source.

2. the control cables use shielded cable, power cable, use a shielded cable or all from the inverter to the motor shield with stuffing tube.

3. electrical cables should be independent of the other cables alignment, the minimum distance of 500 mm. At the same time avoid motor cable and other cables long parallel alignment in order to reduce the frequency inverter output voltage change rapidly produce electromagnetic interference. If the control cables and power cable crossover, should, as far as possible, to make them cross by 90-degree angle. And converter for analog signal line and separated from the main return route alignment, even in the control cabinet to same.

4. and converter for analog signal line preferably enclosureed twisted pair, shielded power cable choice of 3-core cable (its specifications than ordinary motor cable for large files) or to comply with a frequency converter user manual.

3 Inverter control schematics;

1. the main loop: reactor's role is to prevent the converter produces harmonics through power input circuit return to power to affected other affected by electrical equipment requires according to frequency converter size to determine whether you need plus reactor; filter is mounted on the inverter's output, reducing inverter output of high harmonics, when the inverter to the motor of the distance, you should install the filter. Although the inverter itself there are various kinds of protection, but the lack of protection is not perfect, the main circuit breaker to overload, short circuit protection, selection may, in accordance with the inverter capacity. You can use the inverter itself instead of thermal overload protection relay.

2. the control circuit of the frequency inverter with manually switch, so that the frequency of failure can be run manually cut frequency, output voltage, cannot be combined with fixed frequency and frequency to interlock.

Four frequency converter grounding;

Transducer properly grounded is improve system stability, suppressing noise capabilities of an important means. Inverter earthing terminal grounding resistance as small as possible, grounding wire section of not less than 4mm length less than 5 m. Inverter power equipment grounding and bonding of separated and cannot be shared. Signal line shield at one end of the Earth-side received frequency converter, the other end of the floating null. Inverter and similarities between the electric control cabinet.