Caution for Variable Frequency Drives

1. Only trained personnel are authorized to disassemble inverters for repair and replacement of components.

2. After repairing the variable frequency inverter, do not forget to remove any conductive materials such as metal from inside the inverter, otherwise it may cause damage to the inverter.

Before conducting maintenance checks, please confirm the following to prevent electric shock hazards:

①The inverter has been disconnected from the power supply.

② The main control panel charging indicator light is off.

③ Confirm with a multimeter or similar that the voltage between the DC buses has been reduced to a safe level.

4. For variable-frequency drives that have not been used for a long time, use a voltage regulator to slowly increase the input voltage to the rated voltage when powered on. Otherwise, there is a risk of electric shock and explosion.

Siemens variable frequency inverters experiencing overcurrent is a particularly important issue to pay attention to during usage. So, how much do you know about the causes of overcurrent in inverters and how to effectively protect them? Therefore, as a manufacturer of variable frequency inverters, today we are here to discuss this with you. The inverter manufacturer states, the main causes of overcurrent in inverters are as follows?

Non-short circuit overcurrent, mainly caused by: a. severe motor overload. b. rapid motor acceleration. c. high U/f ratio (torque compensation) setting with the motor in light load condition. 2. Short circuit overcurrent, as stated by inverter manufacturers, is primarily due to: a. current overdraw caused by a short circuit on the load side. b. ground fault on the load side. c. formation of a direct connection, where both transistors on the same arm of the inverter bridge conduct simultaneously. As the inverter operates, both transistors on the same arm are in an alternating conduction state. During this process, for some reason (e.g., high ambient temperature), component parameters change, leading to a direct connection. Inverter manufacturers suggest the following protective measures for overcurrent: 1. Under the premise of meeting production equipment and manufacturing process requirements, strive to increase acceleration or deceleration time to avoid overcurrent during acceleration or deceleration.

Siemens variable-frequency drive user programs, which are programs created by users to handle specific automation tasks and downloaded into the CPU. The tasks that the user program needs to complete include the following: ①Determining the CPU restart (hot start) and hot restart conditions (such as initializing signals with specific values). ②Processing process data (such as logical links for generating binary signals, acquiring and evaluating analog signals, binary signals for output, and output analog values). ③Responding to interrupts. ④Handling disturbances during normal program cycles.