Tag: how to

With the rapid development of industrial automation, the variable frequency drive, used for frequency conversion debugging, is thereof widely used. As an important role of frequency conversion speed regulation and energy saving, VFD is mainly used to control the AC motor's power control equipment by changing the frequency of the motor's working power supply. It's not only advantageous for improving the enterprise's process and production level, but also plays an important role in energy saving. But how should we choose an appropriate VFD?

Load capacity of soft starter mainly refers to the overload capacity. Due to different working system, actual load capacity of soft starter is also different. For example, the soft starter generally bears a current of 2~4 times of rated current at starting process, and the duration is within 60s. For long-term working systems, the soft starter actually works under short-term overload during starting process. But for short-term working systems, the soft starter actually works under long-term overload during starting process. Thermal capacity of power semiconductor devices (thyristors) is very small, so the overload capacity of devices mainly depends on the overload capacity of power conductor devices and heat dissipation capacity of soft starters.

With the three-phase reactor, in regulating the speed of the original power frequency excitation, the establishment of the feedback voltage maintains the excitation current in the excitation coil to be in a rather small amplitude, which will basically not exceed the maximum value. It can reach the maximum value unless it is in full-speed operation status. The three-phase reactor is widely used in the elevator, wind power generation, solar power generation, railroad engine, metro, machine tool, welding machine, industrial washing machine, airplane, ship, electromechanical laboratory of the university and other fields.

When we get a pressure transducer, it's necessary to do detection for it. The easiest way to test a pressure transducer is to connect it to a display instrument directly. And check whether the display value changes with the pressure. If it is ok. We have to do further detection for the pressure transducer.

Inverter is a kind of transformer converting the low-voltage DC power (usually such as the power output by the battery) into the high-voltage AC high-frequency power (sine wave AC power of 220V 50Hz or 110V 60Hz). Take a 12V DC to 220V AC car power inverter as example to illustrate the working principle briefly. Firstly, the 12V low-voltage DC power in the vehicle is converted into the high-voltage DC power of around 265V, and then the 265V DC power is converted into the sine wave AC power of 220V, 50Hz. The main inner components of power inverter include the Inverter Bridge, filter circuit, oscillator, control logic circuit and so on. At present, a large amount of various power inverters are filled in various e-commerce platforms. The cheapest one is only tens of dollars, but the expensive ones can cost several hundreds or even one thousand dollars. The maximum power it sustains range from dozens of wattages to several hundreds of wattages. Then, what kind of power inverter can we choose?

As to the ripple wave of the switching power supply, it certainly exists both theoretically and practically. Generally speaking, here are some approaches restraining or reducing it.
Reducing EMI - diode back connection inductance
The metal shell can be adopted as the shield which is used to reduce the radiated interference of the external electromagnetic field. In order to reduce the electromagnetic interference of the power line input, the power input terminal is equipped with the EMI power line filter, just as the below diagram shows (EMI filter is also named as the power line filter). This is also a method usually used to restrain the high-frequency noise.

Confirm the type and concentration range of the gas to be tested. The type of gas encountered in each production department is different. All possible situations should be considered when selecting a gas detector. For example, in the mining environment of coal mines, methane and less toxic alkanes, it is undoubtedly the most suitable choice for the selection of combustible gas detectors. This is not only because the detection principle of the gas detector is simple, the application is wide, and it has the characteristics of convenient maintenance and calibration.

For some Microcontrollers, the resistance of sensor connected must be less than 10kΩ when carrying out the A/D transformation. For example, the resistance of Analog Devices's analog acceleration sensor is 32kΩ. It can’t work normally on the PIC and AVR control board. So it’s suggested to read the controller manual carefully before purchasing the sensor, so as to ensure that the sensor can work normally.

The load cell has a certain overload capacity, but it shall still be prevented from overloading in installation. It should be notified that even a short-term overload can still cause permanent damage to the sensor. During the installation, a pad with the same height of the sensor could be firstly used instead if necessary, then replace the pad with the sensor. In normal operation, the sensor should generally be equipped with mechanical structure for overload protection. If the sensor is fixed with screws, the screw should have a certain fastening torque and screwing thread depth. Generally, high strength screws should be used.

Measurement method of a safety relay's DC resistance with a digital multiemter is similar to that with a pointer multimeter. According to the nominal DC resistance of safety relay, place the multimeter in an appropriate resistor and connect two test pens to the leading wire of the relay coil, then measure the resistance. Comparing the measurement result with the nominal resistance, if the error is within ±l0%, it's normal. If the resistance is obviously smaller, partial short-circuit fault exists in the coil; If the resistance is zero, the coil is short circuited; If the multiemter shows "1", the coil breaks.

Measure coil resistance, resistance of a power relay coil can be measured with the R×10Ω band, thus judging whether the coil has open circuit. Measure actuation voltage and actuation current, with an adjustable stabilized voltage supply and ammeter, the power relay can be input with a voltage while the ammeter can be connected in series to monitor. Slowly increase the power supply. Voltage and record the actuation voltage and actuation current when the power relay is attracted. For accuracy, more operations can be repeated to get the average value. Measure release voltage and release current, connect wires as the test above. When the power relay is attracted, reduce the power supply voltage slowly and record the voltage and current as hearing the relay to release again. More operations can be repeated to get the average value.

Oil leakage is a common problem for gear motor, and the problem may be caused by box quality, lubricating oil quality, oil seal quality and air pressure outside and inside the box. Meanwhile, excessive lubricating oil will also lead to oil leakage. Once the oil leakage occurs in the gear motor, corresponding measures should be taken, and this paper ATO will introduce the solutions for stopping gear motor oil leakage.

Gear motor is widely used in the metallurgy, mine, light industry, chemical industry, steel industry, cement, printing, sugaring, food industry, construction, lifting transportation and fan industry. Working environment of these industry may be damp, and damp environment will directly affect the operation of gear motor. How to keep your gear motor dry when works in such a damp environment?

The infrared thermometer is used for measuring the surface temperature of the object. ATO infrared thermometer is non-contact, handheld and easy to operate, especially suitable for measuring the temperature of various hot, hazardous or hard-to-reach objects. This infrared thermometer consists of Optics, temperature sensors, signal amplifier, processing circuit and LCD display. The Optics collects the infrared energy emitted by the object and focus it to the sensor. Then the sensor transforms the energy into an electricity signal. The signal will be turned into a digital number shown on the LCD after the signal amplifier and processing circuit.

Voltage stabilizer is a kind of power supply equipment which can automatically adjust the output voltage. Its function is to stabilize the power supply voltage which fluctuates greatly and cannot reach the requirement of electrical equipment within its set value range, so that various circuits or electrical equipment can work normally under rated working voltage. With the increasing number of household electrical equipment, the use of voltage stabilizer is more and more extensive. Domestic voltage stabilizer is mainly used to stabilize the voltage of TV, refrigerator, air conditioner, etc. Next, ATO will show you how to install a voltage stabilizer for home.

Load cell is based on the principle that resistance changes when the resistance strain gauge pasting on the surface of elastomer is forced deformation. Load cell converts the change of resistance to mV signal so as to complete the process of converting external force into electrical signal. According to its principle and structure, the fault of strain gauge load cell is often caused by some human or natural factors.

Connect the positive and negative electrode of a 1.5～3V battery with the primary coil L1 and L2 of the transformer respectively, connect the transformer’s secondary side K1, K2 respectively with the positive and negative electrode of a milliammeter. After the loop is well connected, the indicator of milliammeter turns clockwise while connecting K, and turns anticlockwise while disconnecting K, that means the transformer's terminal connecting with the positive electrode of the battery has the same polarity with the terminal connecting with the positive end of the milliammeter, namely L1 and K1 have a same polarity and the transformer is a subtractive polarity. If the indicator turns conversely to the above, the transformer is an additive polarity.

Cause of current transformer burning up

•  Secondary open circuit of the current transformer produces high voltage to burn out the current transformer.
• Long-term use of the current transformer makes the insulation aging, local breakdown or discharge occurs and overvoltage is thereof produced, thus burning out the current transformer.
• The aluminum contact surface of current transformer’s primary connection is seriously oxidized, which results in large contact resistance. The contact resistance gives out heats and burns out the current transformer
• Long-term overload operation makes the current transformer to give out heat, it is thereof burned out.

The vibration frequency of body is not in line with that of grading ring. Owing to the damping of transformer oil, grading ring has a low vibration frequency. And owing to single point welding and aluminum sheet welding, it has a poor mechanical strength. In the long-term operation, the vibration brought by the inconsistent vibration frequency of earth tag of line reactor (aluminum, welding) and grading ring causes metal fatigue and cracks. Solution: fix ascending flange base and body to reduce free-running vibration.