The peripheral configuration of the inverter should pay attention to the problem - Database & Sql Blog Articles

GW MB10F 0.8A 1000V Rectifier Bridge

Probe Current Voltage Pin, 420*4450 Head Diameter 5.0, Over Current and Voltage Pin

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(1) Connect the inverter to a high-capacity power transformer (over 500kVA), or connect a thyristor converter to the same transformer without using a commutating reactor, or use a switching capacitor bank for power factor improvement on the same grid. When AC or DC reactors are used, they also help improve the power factor of the inverter’s input side and reduce harmonic currents.

(2) Install a low-voltage circuit breaker and an AC contactor with short-circuit and overload protection between the inverter and the power supply to prevent accidents if the inverter fails. The emergency stop function of the control system should disconnect the AC contactor on the inverter’s power side, completely cutting off the power to ensure equipment and personnel safety.

(3) Ensure that the inverter’s input terminals R, S, T and output terminals U, V, W are correctly connected. The input terminals are connected to the three-phase rectifier bridge, while the output terminals are connected to the motor. Incorrect wiring can lead to failure to control speed, motor not running, and potential damage to the inverter.

(4) Avoid using the main power switch to start or stop the inverter when it is frequently operated. Instead, use the start/stop button on the control panel or the SF/SR terminal. Frequent starting causes the electrolytic capacitor to heat up, reducing its lifespan and potentially damaging the inverter.

(5) The “N” terminal of the inverter is the low-level point of the DC link. It must not be connected to the neutral or ground wire in a three-phase four-wire system. Doing so may cause a short circuit and damage the rectifier bridge.

(6) Do not install electromagnetic contactors on the inverter’s output side. If necessary, ensure that the contactor is only switched when the inverter is stopped. Switching during operation can generate high overvoltage, damaging the inverter’s power components. Always block the inverter’s power transistors before switching the contactor.

(7) For inverters with internal braking units and external resistors, ensure correct wiring of the braking resistor. It should be connected between P and DB, not between P and N. Connecting it incorrectly can cause the inverter to load even when not running, leading to overheating or damage.

(8) In multi-speed motors controlled by variable frequency drives, do not change the pole pairs during operation. Changing the winding configuration while the inverter is running can cause large inrush currents, leading to tripping or damage. Always wait until the inverter has stopped before changing the motor windings.

(9) Properly use mechanical brakes in variable frequency systems. If the brake coil is connected to the U, V, W outputs, it will remain engaged at low speeds, causing the inverter to overload. Instead, connect the brake coil to the input terminals R, S, T to avoid this issue.

(10) When operating at low speeds, self-cooled asynchronous motors may experience increased temperature due to reduced cooling efficiency. This can affect performance. To prevent overheating, implement forced cooling methods when running under constant torque loads at low frequencies.

(11) Long cables between the inverter and motor increase distributed capacitance, causing excessive peak current and possible tripping. Use output chokes, du/dt filters, or sine-wave filters to limit this current. An output filter reactor helps compensate for line capacitance and suppress harmonics, especially in multi-motor systems.

(12) Avoid installing power capacitors, surge protectors, or noise filters on the inverter’s output side, as they may cause damage to the inverter or other components.

(13) Inverters with PWM modulation can produce leakage current due to distributed capacitance in the wiring and motor. To reduce this, minimize cable length and lower the carrier frequency. For safety, use an earth leakage circuit breaker on the inverter’s input side. The sensitivity current should be calculated based on the inverter’s specifications or estimated at 20mA per unit for specialized breakers and 50mA for general ones.