(1) Fault 1: Touch deviation

Phenomenon 1: The position touched by the finger does not coincide with the mouse arrow.

Reason 1: After installing the driver program, there was no vertical touch on the center position of the bullseye during calibration.

Solution 1: Recalibrate the position.

Phenomenon 2: Some areas have accurate touch, while others have deviation in touch.

Reason 2: The accumulation of a large amount of dust or scale on the surface acoustic wave reflection stripes around the surface acoustic wave touch screen affects the transmission of acoustic signals.

Solution 2: Clean the touch screen, paying special attention to cleaning the sound wave reflection stripes on all sides of the touch screen. When cleaning, disconnect the power supply of the touch screen control card.

(2) Fault 2: Touch screen does not respond to touch

Phenomenon: When touching the screen, the mouse arrow does not move or change position.

Reason: The reasons for this phenomenon are as follows:

① The accumulation of dust or scale on the sound wave reflection stripes around the surface acoustic wave touch screen is very severe, causing the touch screen to malfunction;

② Touch screen malfunction;

③ Touch screen control card malfunction;

④ Touch screen signal line malfunction;

⑤ Serial port malfunction;

⑥ Operating system malfunction;

⑦ Touch screen driver installation error

Common troubleshooting methods for Siemens touch screens

Common troubleshooting methods for Siemens touch screens

1. The single-phase or multi-phase fault information is displayed as "inverter u" or "inverter v or w". The reason is that the inverter has a single-phase or multi-phase fault. If the peak current i of a switch tube is greater than 3inrms, which is the rated current of IGBT, or if there is a problem with the auxiliary power source of one phase of the inverter gate, this situation will occur. After this fault occurs, it can cause a short circuit at the output end of the frequency converter, or due to incorrect controller settings, it can lead to significant motor vibration. There are generally two situations during maintenance:

(1) When triggering a board fault in a Siemens inverter for pulse width modulation, the duty cycle of the pulse series is arranged according to a sine law. The modulation wave is a sine wave, and the carrier wave is a bipolar isosceles triangle wave. The intersection of the modulation wave and the carrier wave determines the pulse series of the output phase voltage of the inverter bridge. The door control board is implemented through a large-scale integrated IC (ASIC), which includes a digital frequency generator with a resolution of up to 0.001Hz and a maximum frequency of 500Hz, and a pulse width modulator that generates a three-phase sine wave system. This modulator operates asynchronously at a constant pulse frequency of 8kHz. The voltage pulses generated by it alternately pass through and turn off two switching power devices on the same bridge arm. This circuit board has malfunctioned and cannot generate voltage pulses normally. It needs to be replaced and repaired.

The inverter device used by Siemens frequency converter is insulated gate bipolar transistor IGBT, which has the control characteristics of high input impedance and small gate current, resulting in low driving power and can only operate in switch state, not in amplification state. Its switching frequency can reach a high level, but its anti-static performance is poor. Whether IGBT components are faulty can be measured and judged using an ohmmeter. The specific steps are as follows:

● Disconnect the power supply of the frequency converter;

● Disconnect the controlled motor;

Measure the impedance of the output terminal and the DC connection terminals a and d with an ohmmeter (see attached figure), each by changing the polarity of the ohmmeter twice. If the IGBT of the frequency converter is intact, it should be: low resistance from u2 to a, otherwise, high resistance; From u2 to d high resistance value; On the contrary, low resistance. The same goes for other forms. When the IGBT is disconnected, both times it has a high resistance value, and if there is a short circuit, it has a low resistance value.

The fault information of the energy consumption resistor is displayed as "pulsed resistor", which means that the energy consumption resistor is overloaded. There are three reasons for this: high regenerative braking voltage, high braking power, or short braking time. The energy consumption resistor is an additional component. Due to the large inertia load of textile and chemical fiber equipment, a high-power switch tube and energy consumption resistor are connected in parallel to the DC part of the frequency converter to the DA wiring. Its main function is to dynamically limit the overvoltage on the DA line when the power is turned on, off, or loaded. But when the braking current exceeds the rated value, the operation will be interrupted. There are usually two situations:

(1) Energy consuming resistor malfunction. In actual use of frequency converters, a pulse resistor with a resistance of 7.5 ω/30kw is selected. After several years of use, a frequency converter experienced a decrease in resistance due to the high number of start stop cycles, which caused the resistor to heat up. But Siemens frequency converters have strict requirements for their resistance, which must be greater than or equal to 7.5 Ω. Therefore, although the resistance value of the energy consumption resistor of this frequency converter is about 7.1 Ω, the above-mentioned faults will still occur and it cannot start up normally. Then switch to a high-power resistor with a resistance of about 8 Ω before starting up.

(2) IGBT malfunction. There is a fault in the IGBT part of the inverter, which can cause excessive regenerative feedback current and overload of the energy consuming resistor.

4 . The overheating fault information is displayed as "over item operation" because the cooling temperature of the inverter is too high. The heating of the frequency converter is mainly caused by the inverter device, which is also the most important and fragile component in the frequency converter. Therefore, the temperature sensor (NTC) used for temperature measurement is also installed in the upper part of the inverter device. When the temperature exceeds 60 ℃, the frequency converter predicts an alarm through a signal relay; When the temperature reaches 70 ℃, the frequency converter automatically shuts down for self-protection. Overheating is generally caused by five situations:

(1) The ambient temperature is high. Some workshops have high environmental temperatures and are too far away from the control room. In order to save cables and facilitate on-site operation, frequency converters have to be installed on the workshop site. At this point, the air inlet of the frequency converter can be equipped with a cold air duct to help dissipate heat.

(2) Fan malfunction. The exhaust fan of the frequency converter is a 24V DC motor. If the fan bearings are damaged or the coils are burned out, and the fan does not rotate, it can cause the frequency converter to overheat.

(3) The heat sink is too dirty. There is an aluminum sheet heat dissipation device installed behind the inverter of the frequency converter. After a long period of operation, due to the effect of static electricity, the outside will be covered with dust, which seriously affects the effectiveness of the heat sink. So it is necessary to blow and clean regularly.

(4) Load overload. The load carried by the frequency converter is overloaded for a long time, causing heating. At this point, it is necessary to check the electric motor, transmission mechanism, and the load it carries.

(5) Temperature sensor malfunction. NTC is a negative temperature controller whose resistance decreases as the temperature increases. This situation is relatively rare.

5. The ground fault information is displayed as "ground fault", which refers to the grounding of the output terminal of the frequency converter or the generation of a large capacitance due to the cable being too long. There are several types of grounding faults:

(1) The motor is grounded. During the operation of the motor, due to the heating of bearings or coils, the grounding or insulation performance of a certain phase of the motor coil deteriorates, resulting in grounding faults. This requires maintenance of the motor.

(2) The connected cable is grounded. Damaged or overheated cables connecting the motor and frequency converter can lead to poor insulation performance and also easily cause grounding faults.

(3) Internal malfunction of the frequency converter. After prolonged operation of the frequency converter, the insulation performance of the internal circuit board deteriorates, which can also cause a decrease in insulation resistance to ground, resulting in a ground fault. At this point, it is necessary to perform insulation treatment on the circuit board of the frequency converter. Spraying insulation paint after power failure can eliminate this fault