FC3U12STMF

FC3U12STMF is a device of the intelligent electrical component and the main use in the field of HVAC industry to carry out the medium or large capacity motor. It combines with frequency inverter and overload protection to build a perfect control device. Equipped with multiple protection functions that improve the working of the motor, the working principle of the programmable controller will be introduced in the following part.

The input part of the device is connected to the power line which is supplied by capacitor, transformer, or relay-contact input. The electricity passes through the RFI filter at the entrance of the power line, the input process via the analog power supply or the galvanic isolation unit, the filter is used to remove the voltage interference. Generally, power lines have only one phase, so the current flow in the complete circuit in one direction is converted to two alternating current signals to supply to the two input terminal pins of the device.

The power supply of the inverter is divided into two parts. The direct current voltage is stabilized by a parallel resistance capacitor network and the pulsating voltage is divided into an AC and DC component that goes separately into the inverter. In the input part of the inverter, an input rectifier is connected to the frequency and flux-producing components. The rectifier forms a DC voltage loop for the inverter motor, which regulates the current speed and direction with the help of the rectifier network.

The output part of the inverter is connected to an amplifier in which the voltage reference and the voltage correction signal are combined. The amplifier will then output the corrected signal to the inverter. The frequency of the voltage output of the inverter is determined by the input signal, and will generally be 0 Hz when the motor is not running and between 1 and 1000 Hz when the motor is running. The combination of DC voltage and high frequency outputs from the output transformer, the power amplifier and other related components form the frequency control output.

The overload protection is also an important part of the device. It protects the motor from any damage due to excessive current by cutting off or reducing the power supply. The motor is supplied with a mechanical protection system as a secondary level if the primary protection fails. The frequency inverter will monitor the motor load and reduce the voltage output if the current exceeds a pre-set value.

In conclusion, the FC3U12STMF is a device specifically used for HVAC industry. Its working principle is that the device takes in the power line, filter the voltage interference and converts the current into two alternating current signals. In the inverter part, the current speed and direction is regulated. The combination of DC voltage and frequency outputs from output transformer and power amplifier is used to form the frequency control output. The overload protection system of the device is used to protect the motor from any damage due to excessive current.