There should be no open circuit on the secondary side of the current transformer in operation. Once the open circuit occurs on the secondary side, high temperature caused by excessive iron loss may burn out the current transformer or enhance the voltage of secondary winding, thus breaking down the insulation and leading to the danger of high voltage electric shock. Therefore, when replacing a meter such as an ammeter, active power meter and reactive power meter, please ensure the current circuit in short circuit before operation. After replacement, connect the meter in the secondary circuit and then remove the short-circuit wires while checking if the meter is normal. In case sparks appear when removing the short-circuit wires, that means the current transformer disconnects, please short the loop again and confirm the meter loop isn’t an open circuit. When removing the short-circuit wires of the current transformer, please stand on an insulated pad and consider a protector to stop the current transformer loop. When it finishes work, the protector can be put in use.
Blog
In industry, the pH meter is used more frequent as a pH measuring and analyzing instrument rather than the pH test paper and standard colour chart. The digital pH meter display screen can accurately show the pH value on real time, the error is greatly increased by one order of magnitude than that of pH test paper. Moreover, it can also realize the automatic control of pH value and pH value alarm. But due to the service life of pH electrodes, it is easy to break down, as a result, users have to pay much money in replace new pH electrodes. Next we will introduce the selection experience of pH electrode in several typical industries, so as to provide reference for users.
Machine vision has been favored by many industries, such as industrial production and scientific research, for its advantages in performance and imaging. However, clear and accurate imaging effect of machine vision is also inseparable from the imaging technology of industrial lens. It’s reported that factors affecting the imaging effect are the lens, aperture and depth of field. At present, what are mostly focused are basically two technical parameters, namely the aspherical lens and large depth of field. This paper mainly analyzes the effect of above two technologies on the imaging effect of machine vision.
A pH electrode is a part of the pH meter contacting with measured substance. It's used to measure the electrode potential. Generally, there are two methods to measure the pH value of the aqueous solutions, namely Colorimetry (pH test paper and cuvette) and potentiometric method. The latter is the only way to realize continuous on-line measurement and process monitoring. Moreover, it can obtain accurate and repeatable pH value. The electrode used in the potentiometric method is called as primary battery, which is a system used to converse the chemical reaction energy into electrical energy, voltage of the primary battery is called for electrodynamic force (EMF).
UPS power system consists of 4 parts: rectification, energy storage, transformation and on-off control. UPS realizes the function of voltage stabilization with rectifier, which is generally a silicon-controlled rectifier (SCR) or high-frequency switching rectifier. The rectifier controls the output amplitude according to the change of external power supply; when the external power supply changes (the change should meet the system requirements), it outputs a rectified voltage whose amplitude keeps unchanged. Purification function of UPS is completed by the energy storage battery. As the rectifier cannot eliminate instantaneous pulse interference, the rectified voltage still has interference pulse. Energy storage battery can not only store DC power, but also plays a role of large-capacity capacitor for the rectifier, its equivalent capacitance is proportional to the capacity of energy storage battery. As the voltage at both ends of the capacitor can’t change suddenly, the pulse interference is eliminated due to the smoothness property of capacitor for pulses, thus realizing the purification, as well as the shielding against interference. Converter guarantees a stable frequency of uninterruptible power supply. Frequency stability is determined by the stability of the converter's oscillation frequency. To facilitate daily operation and maintenance of UPS power system, an operating switch, automatic bypass switch after fault self-checking, overhaul bypass switch are designed in this system.
There's no display on the panel after the UPS starts, UPS doesn't work?
Fault analysis: the fault may lie in power input, battery and power detection, battery voltage test circuit:
- Check if the power input fuse is burned out.
- If the fuse works normally, check whether the battery fuse is burned out, because some uninterruptible power supply may close all outputs and display when it can't detect a voltage.
- If the battery fuse is complete, please check if the power detection circuit works normally. If it doesn't work normally while UPS can't start without power supply, UPS will also close all outputs and display.
- If the power detection circuit works normally, please check if the battery voltage test circuit is normal.
A built-in power lightning protection device should be used in the internal power supply of the electrical equipment which functions as the final line of defense, so as to completely eliminate the tiny transient overvoltage. The power lightning arrester used at this level requires a maximum impact capacity of 20KA per phase or less, and the required limit voltage should be less than 1000V. It is necessary to provide class-III protection for some particularly important or sensitive electronic devices, as well as to protect the electrical equipment from transient overvoltage produced within the system.
First, according to the power of the purchased voltage stabilizer, select the appropriate wire to connect the input and output terminals of the stabilizer. (Note: The wiring should be strictly in accordance with the wiring tag of the stabilizer when installing. Pay special attention to the fact that the live and neutral wires must not be reversed. The neutral and ground wires must not be confused. The ground and neutral wires cannot be omitted). Turn on the voltage stabilizer switch, the voltage meter output on the panel should dispaly 220V, and the power indicator on the panel is on, indicating that the voltage stabilizer has been working normally. If it is necessary to adjust the output voltage, adjust the voltage potentiometer of the circuit board of the machine and adjust it clockwise to increase the output voltage. Adjust counterclockwise to reduce output voltage (turn off load when adjusting).
Brushless DC motor (BLDC) uses electronic phase-changing circuit to supply DC power to motor rotor winding. Since there is no mechanical brush, it is called brushless DC motor. Because of brushless DC motor with high efficiency and accurate control performance, and can use the electronic packaging to meet the needs of security specification features. Under the demands of global energy conservation and carbon reduction, it is widely applied in the field of air conditioning, such as common DC inverter, brushless DC technology; it also can be used in hybrid electric vehicle and some appliances of high economic value, such as electric fans and other products.
Magnetic flowmeter is a widely used instrument that plays an important role in the measurement of waste water and sewage. However, due to mistakes in model selection, installation and use, it may eventually affect the measurement accuracy of magnetic flow meter, causing deviation of measurement data and even damaging to the flowmeter. Now ATO will guide you to analyze why measurement errors in magnetic flow meter happen and how to troubleshoot these problems.
- The liquid to be tested contains bubble.
- The liquid to be measured is non-full in pipe.
- Short circuit effect of conductive sediments
- The liquid generates crystallization.
- Liquid conductivity exceeds allowable range.
- Spatial electromagnetic disturbance
- Unsymmetrical flow of the fluid to be measured
- Vibration of the installation site affects the accuracy of magnetic flowmeter.
What is the principle of the chemical element analysis instrument?
Chemical analysis instrument is mainly used for in-site measurement of elements in metal materials in the military industry, aerospace, iron and steel, petrochemical, power, pharmaceutical and other fields, it's an indispensable tool for rapid identification of materials in the industrial and military manufacturing fields accompanying the rise of the world economy.
Principle of chemical element analysis instrument.
A pH meter is an digital instrument used to test and monitor the pH value of a solution. It works by the principle of primary battery, of which the electromotive force between two electrodes is based on the Nernst Law. Electromotive force of primary battery is affected by both property of electrodes and hydrogen ion concentration in the solution. There is a correspondence relationship between the electromotive force and hydrogen ion concentration of the primary battery, namely negative logarithm of the hydrogen ion concentration is equal to the pH value.
Compared with other motors, the ATO induction motor has the advantages such as simple structure, convenience in manufacture, use and maintenance, high operational reliability, light weight, low cost. Taken the ATO three-phase induction motor as an example, compared with the DC motor with the same power and speed, the former weight is only half of the latter at one-third cost. It also has the load characteristics of constant speed that can satisfy machinery driving requirement of a majority of industrial and agricultural production. Its limitation is that due to the poor speed controlling performance caused by the fixed slip between its rotate speed and the synchronous speed of its rotating magnetic field, so it is not so economic or convenient as direct current motor under the usage occasion that requires a wider range of smooth speed control such as rolling mill, winding engine, large size machine tool etc. In addition, induction motors draw reactive power from the power system during the operation, resulting in the deterioration of power factor of power system. Therefore, on the occasion of high power and low speed such as driving ball grinding mill and compressor, using synchronous motors is more reasonable.
Safety relay can be classified into electromagnetic safety relay, thermal reed relay and solid-state relay. The working principle of safety relays can also be roughly divided into three types. Safety relay is composed of several relays and circuits, so as to supplement each other's abnormal defects and achieve the complete function of relay with correct and low faulty operation, so as to make the error and failure value become lower, thus reaching higher safety factor. Therefore, multiple safety relays should be designed to protect different grades of machinery. It is used to mainly protect the mechanical operators who perform operation under different levels of risk.
As a common electrical actuator, stepper motor is widely applied in automatic control field. Stepper motor needs to be equipped with a special drive power the output of which is controlled by external pulse signal and direction signal. Each pulse signal can make stepper motor rotate a fixed angle, which is called step angle. Total angle and speed of rotation respectively depend on the number and frequency of pulse. The direction of rotation depends on direction signal. For a equipment with a known transmission ratio, the movement distance and speed of its parts can be controlled by controlling the number and frequency of pulse without the requirements for the feedback of distance and speed signals; and direction signal can control moving direction. Therefore, open loop control is a simple and economic electronic control technical scheme.
AC contactor is generally classified into class I, class II, class III and class IV according to the type of load, and they are respectively recorded as AC-1, AC-2, AC-3 and AC-4. AC-1 AC contactor corresponds to non inductive or micro inductive load as its control object, such as the filament lamp, resistor furnace. AC-2 AC contactor is used for starting and stopping of wound asynchronous motor. Typical application of AC-3 AC contactor is the operation of squirrel-cage asynchronous motor and the break in operation. AC-4 AC contactor is used for starting, reverse braking, reversing and jog of cage asynchronous motor. All ATO AC contactors with 24V/110V/220V coil operating at AC-3 380V or 660V.
There is no signal waveform on the screen when collecting signals?
1. Check whether the detector is normally connected to the signal wire.
2. Check whether the signal wire is normally connected to the BNC (namely channel connector).
3. Check whether the detector is normally connected with the object under measurement.
4. Check whether the object under measurement produces a signal (Signal channel can be connected with the fault channel to find out the fault).
5. Collect the signal again.
6. Check the state of the trigger mode.
Brushless DC motor (BLDC) replaces the mechanical commutator with electronic commutator, just because of the electronic commutator, the BLDC motor needs a controller to drive the circuit. ATO BLDC motor not only has a speed regulation performance as the DC motor, but also has the advantages of simple structure, no commutation spark, reliable operation and easy maintenance as the AC motor, so it’s widely used in industrial equipment, instrumentation, household appliances, robots, medical equipment and other fields. The commutation circuit of BLDC motor consists of two indispensable parts: drive and control. Particularly, the two parts are integrated into a single ASIC for low power circuit.
As we all know, the direct starting current of motor is 4-7 times rated current, the motors with a low power (generally lower than 7.5kW) have few influences on power grid and are allowed to start directly, but the large motors with high power (rated current 100A) have the instantaneous current of hundred of amperes and are not allowed to start directly because such high current has a high impact on power grid and can influence the normal work of other loads on the same power grid.
Different motors of the same rated horsepower may have different starting currents, torque curves, speeds and other variables. NEMA (National Electrical Manufacturers Association) has A, B, C, D four different designs for electric motors.
NEMA Design B: Is the most common design of electrical motors and ATO single phase AC induction motors are of NEMA design B. Its starting torque is similar to that of design A, but sometimes still lower, providing a relatively low starting current. However, in industrial application, it locks locked rotor and still allows starting load. The rotating-speed difference is lower than or equivalent to 5%. The electric efficiency and full-load power factor are relatively high. The typical applications include pump, fan and machine tool.
