What Are Terminal Buttons?

The input terminal is the interface for the LCD TV to receive signals. Standard video input AV terminal, DV input terminal, S video input terminal, video color difference input terminal, VGA input terminal are usually used. The LCD TV can be easily connected to other supporting equipment through these input terminals.

Common input terminals ^[1]

Digital input terminal practical application

The digital input terminal ^[2] of the inverter is used to control the motor, which is widely used in actual production and life.

Between the No. 5 and No. 9 terminals of the digital input of the inverter, connect the normally open auxiliary contact of the AC contactor KM1 that controls the motor's forward rotation; between the No. 6 and No. 9 terminals, the human control the motor to reverse Normally open auxiliary contact for AC contactor KM2. When the forward start button is pressed, the KM1 coil is energized, the KM1 normally open auxiliary contact is closed, the inverter's terminal 5 receives the control signal, and the motor runs forward at the frequency set by the inverter. When the stop button is pressed, the KM1 coil loses power. Electricity, the KM1 normally open auxiliary contact is disconnected, the No. 5 terminal of the inverter loses the control signal, and the motor stops according to the set stopping mode. The control signal for motor reverse rotation is connected to terminal 6 and the circuit operation process refers to the motor forward rotation process.

Input terminal fault detection and fault phenomenon

The circuit uses the AC contactor coil to energize the auxiliary normally open contact to close, so that the No. 5 terminal gets the control signal. Although the AC contactor coil is connected to AC 220V voltage, the voltage between the control terminals of the inverter is 24V. In the circuit connection, due to incorrect wiring, the 220 volt voltage was connected to terminal 5 by mistake, which caused the power supply of the inverter to trip, and a burning odor could be smelled at the port. After the inverter discharge is completed (the inverter is powered off for at least 5 minutes), first use the pointer multimeter x10 (or x100) ohms to measure the input power terminals L1, L2, L3 to the DC bus terminals DC +, DC1 Forward and reverse DC resistance, and then measure the forward and reverse DC resistance between the motor terminals LJ, V, W at the output end and the DC bus terminals DC +, DC-1, the measurement results show normal, so you can judge the upper and lower arms of the rectifier bridge 6 6 rectifier tubes and 6 freewheeling diodes of the upper and lower bridge arms of the inverter circuit are intact. According to the failure phenomenon and the results of the external terminal detection, the I / 0 board of the inverter is preliminarily judged to be damaged. The fault was not repaired, so as to avoid secondary damage to the inverter, and it was not replaced with other digital terminals for power-on test.

Input terminal results and precautions

The chip components of the inverter I / 0 circuit board are small in size, the components are arranged closely, and the spacing is narrow. Improper welding can easily cause short circuits and copper foil shedding. The removal or welding of burned components requires professional tools and Skilled technology. The broken wires are very thin and the spacing between the wires is very small. Repairing and welding the broken wires is also quite troublesome and requires professional maintenance. Even if repaired, the inverter is likely to have instability. Buying new circuit boards is also more expensive. Therefore, when using the external terminal control mode of the inverter, it is necessary to strengthen the precautions. In addition to careful inspection and inspection of the circuit, using a relay with the same voltage level as the external terminal as the control switch instead of the AC contactor can provide good protection. Avoid the above-mentioned artificial failure to lead abnormal voltage to the inverter.

The damage caused by the abnormal external voltage caused by the digital terminals is serious. The external terminals of the 440 inverter also include analog input, output terminals, digital output terminals, etc. When using these external control terminals, be sure to read the instruction manual carefully, carefully understand its function and structure, design the control circuit and ensure the installation is correct.