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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.

Automobile image sensing has a wide range of applications, the image sensor with excellent performance and advanced image processing capability can enhance driving safety and improve users’ riding experience, it has become a popular technology in the automotive field in recent years.
Main application fields of automobile image sensor
Automobile image sensors has extensive applications, including the visual application, such as the Rear View Camera, front/rear/ overlook/ panoramic parking image, mirror replacement, passenger monitoring, fatigue driving monitoring, dashboard control, DVR, gasbag; advanced driving auxiliary system (ADAS), such as forward collision warning, lane departure warning, automatic long light control, traffic signal recognition, pedestrian detection, adaptive cruise control, blind spot detection, night viewing.

Electromagnetic clutch‍‍
Any clutch can complete the function of mechanical transmission, electromagnetic clutch controls the engagement and separation of the clutch through the power failure of the coil. For the common dry monolithic electromagnetic clutch, when the coil is powered on, magnetic force is generated to pull the “armature” piece, so that the clutch is engaged; When the coil is powered off, the magnetic force disappears and the “armature” returns back, the clutch is separated. This is a power failure working mode, beside this, the electromagnetic clutch can also work in power break combination, which will not be introduced here.

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.

Displacement sensor, also called linear sensor, is a linear unit sensing metal. The function of sensor is to transform the tested physical quantity into electric quantity. The working principle of straight line displacement sensor is same as that of slide rheostat. It is used as voltage divider to present the actual position of tested position through relative output voltage. There are a few requirements for the work at the position:

Oil replacement and drying treatment of electric reactor: if the long idle time or operation time or other nature and human factors cause insulation deterioration of line reactor, water inflow or oil deterioration, oil replacement and drying treatment should be conducted to line reactor. Oil replacement of line reactor: lift the body of line reactor out, drain sump oil, wash oil tank, and wash the greasy dirt on the body of electric reactor if any. After drying, fill electric reactor with oil and replace all grease-proof rubber seals. Theline reactor can be operated only after passing the test.
Drying treatment of line reactor: its body has many drying methods. Users can adopt zero phase sequence drying method, eddy drying method, short circuit drying method and oven drying method when they dry line reactor by themselves.

The common line reactors in electrical power system include series reactors and paralleling reactors. Series reactors are mainly used to limit short-circuit current or ultraharmonics in filter by connecting with capacitor in series or in parallel. The line reactors in power grid of 220kV, 110kV, 35kV and 10kV are used to absorb the idle work of charging capacity of cable line. Operating voltage can be adjusted by adjusting the number of line reactors in parallel. Ultra-high voltage paralleling reactor can improve the operation conditions relating to reactive power of electrical power system including:

The functions of input line reactor
It can restrain harmonic current, improve power coefficient, weaken surge voltage in input circuit, the impact of current on VFD, the influences of power voltage, limit current surge caused by grid voltage change and switching surge, spike pulse or voltage defects in phase change of rectifying circuit, effectively protect VFD and improve power coefficient. Input line reactor not only can stop the disturbance from power grid but reduce the pollution of power grid by harmonic current produced by rectifying unit.

The calibration of load cell and digital display controller is mainly to confirm the weighing signal of zero point and full range of the load cell. That is to say, telling the digital display controller what are zero weight signal and full range weight signal received from the load cell. In this way, the digital display controller will display the value according to the detected weight, or export the matching weight signal to the PLC/DCS control system.

Contact system maintenance

• Check whether the position of the movable and static contact points is aligned, whether the three-phase is closed at the same time; Adjust the contact spring in case of any problem.
• Check the wear degree of contact points, the wearing depth shall not be more than 1mm. In case of contact burning or welding falling, please replace timely; Slight burning will not affect the application. The sand paper can not be used to clean the contact, a shaping file is suitable.
• The resistance shall not be less than 10MΩ when measuring the interphase insulation resistance;
• Check whether the auxiliary contact acts flexibly, the contact travel should comply with the specified value. Check whether the contact is loosening, maintain or replace timely in case of any problem.

Gas flow sensor is mainly composed of a housing, a front guide frame, an impeller, a rear guide frame, a tightening ring and a magnetoelectric induction transducer with an amplifier. The new generation of high precision and high reliability gas flow sensor is designed in accordance with the advanced technology at home and abroad, and is independently developed based on the theories of gas dynamics, fluid mechanics and electromagnetics. It has excellent performance for low pressure and high pressure measurement, multiple signal output and low sensitivity to fluid disturbance, and has been widely used in the measurement of natural gas, coal gas, liquefied petroleum gas and light hydrocarbon gas.

Helical slit flexible coupling
Helical slit flexible couplings are usually called as integrated slit cutting coupling or flexible coupling, they often have good performance and cost economy, and are regarded as preferred products in many applications.
The integrated design of a complete aluminum alloy bar makes it to have advantages of zero backlash drive moment and no maintenance. The helical slit flexible couplings can be broadly divided into two basic series: single head helix slit and multi head helix slit. It has large flexibility but low additional bearing load. Such a slit design is particularly suitable for handling the angular deviation and axial deviation, but not suitable for parallel displacement deviation, because the single head helix slit would produce multiple directional bending when handling parallel deviation, which may result in the excessive stress concentration and earlier damage of the parts.
Multi head helix slit coupling reduces the slit length without losing the ability to rectify deviation, the multi head helix slits are intertwined to enhance the torsional rigidity of the coupling, thus ensuring that the coupling can still withstand considerable torque when it has great rectifying capability. This performance makes it suitable for light load applications, such as the connection between the servo motor and the screw. However, such a design also has its shortcomings. The additional bearing load will increase as the size increases. But in most cases, as the installation error is smaller, the bending moment is also very small, thus ensuring low additional bearing load.

Humidity sensor is widely applied in many fields, particularly in the fields that record the temperature and humidity changes in real time. The temperature and humidity sensor can scientifically and effectively manage, analyze and summarize the recorded contents.

Application in the management of museum cultural relics and archives
It's another area for the application of temperature and humidity sensors. The archive papers can be kept for a longer time at a suitable temperature and humidity condition, once the temperature and humidity condition is changed, the paper will be crisp, important materials will also be lost. So it’s necessary to record the temperature and humidity of the archives, prevent the occurrence of malignant accidents. Application of temperature and humidity sensors simplifies the temperature and humidity record, saves the cost of cultural relics preservation and makes the work more scientific, prevents it from being disturbed by too much human factors.

After connecting the wires accurately according to the wiring diagram and powering on, the meter displays the thermocouple graduation firstly and then the range, measure the nixie tube on the lower part of the meter to display the setting temperature, and measure the nixie tube on the upper part of the meter to display the measuring temperature. If the upper nixie tube doesn’t display the temperature of the heating body but the other states such as “OVER”, “0000” or “000”, meaning that the output part of the meter goes wrong, following inspections shall be made:
Remove the thermocouple from the thermocouple output end of the instrument and then short circuit the thermocouple output end of the instrument with a wire. If the temperature showed on the upper nixie tube is close to the room temperature after powering on, meaning that exterior wire connection of the thermocouple disconnects, replace with a same thermocouple. If it keeps a same state as previous, meaning that the output end of the instrument is damaged in transportation, change an instrument please.