AQ: Figure out variable speed drives failures
If there is frequent current-limitation or overcurrent alarm during the variable speed drive running, we should check the loads and inverter IGBT module is normal or not, if its good, then the failure is the Hall magnetic compensation current sensor damaged on the control circuit of the variable speed drive. Hall magnetic compensation current sensor is a device to measure the current value of sinusoidal and non-sinusoidal periodic, which can truly reflect the real current waveform, to provide a control and protection signal to the variable speed drive. Generally, this device in variable frequency drive mostly is Swiss company LEM LA series components, LA Series Hall current sensor magnetic compensation can be divided into three and five terminals, for different variable speed drives capacity, the Hall current sensor magnetic compensation also is difference.
Electronic components are very sensitive to static electricity, it will cause electronic components soft breakdown and then cause the circuit board cannot work. So we should be careful when we replace the circuit board, and ensure wearing grounding wrist strap before working, make sure the strap ground directly and human body is at zero potential, in order to prevent body’s electrostatic damage to the circuit board. If there is no grounding wrist strap, we should touch the variable speed drive metal cabinet before replacing the circuit board, to ease static electricity through the variable frequency drive enclosure.
