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The storage method and maintenance of the instrument

Release date:2017/11/3 16:01:33    Times of browsing:

The daily maintenance work of the instrument is very important for prolonging the normal working life of the instrument, reducing the failure of the instrument, ensuring the safe use and ensuring the accuracy of the measurement. The maintenance measures can be roughly summed up as follows.

  

  1.Dustproof and dust removal

  

  To ensure that the instrument is in good standby condition, first of all, it should keep its appearance clean. Therefore, dustproof and dust removal are the most basic maintenance measures.

  

  Most of the meters are equipped with special dustproof cover, and the instrument should be covered after using the meter. In the case of using plastic cover, it is best to wait for the temperature drop before adding the cover, so that the water vapor is not easy to distribute. If there is no special dust cover, we should also try to cover it or put the instrument into the cabinet; the glass fiber cover is harmful to the health of the users, and the glass fiber is not easy to be removed in the instrument, and it will even cause serious problems such as bad contact and dryness of the components, because it is strictly prohibited. In addition, instruments should be banned from shelving on the floor of cement or walls.

  

  Usually use brush, cloth, or gauze coated with insulating oil, such as transformer oil, to wipe the appearance of the meter clean. But do not use water wet cloth to wipe, avoid water vapor immersed in the instrument and damp, and prevent the case from rust. If the instrument shell is found to be attached with rosin and should not be scraped with the blade, it should be erased with a cotton ball with alcohol; if attached to the welding oil, it should be erased with gasoline or carbon tetrachloride; if attached to solder, it can be carefully removed with the blade. For the ash inside the instrument, it is usually used to overhaul the instrument, and use the "skin tiger" or the long hair brush to clean it. It should be pointed out that when cleaning the internal dust of the instrument, it is best not to change the position of circuit elements and wiring, and to avoid pulling out electronic tubes, quartz crystal and other inserting devices. Marking should be made in advance if necessary so as to avoid inserting the wrong position when reset.

  2.Moisture-proof and flood tide

  

  

The insulation strength of the internal power transformers and other wire winding devices (such as wire wound resistors, potentiometers, inductor coils, moving coil of the head, etc.) often decreases because of dampness, leakage, breakdown, even mildew breakage, so that the instrument is broken down. Therefore, the instrument must take effective measures for moisture-proof and moisture repel.






First of all, where the instrument is stored, it is better to choose a more dry room upstairs. The doors and windows should face south to the East.






In the instrument room, or in the cabinet for storing instruments, a "silica gel" cloth bag should be placed to absorb moisture in the air. Regular checks should be made if silica gel is dry. If it is found that the caking of silica gel becomes yellow, it indicates that its water absorption function has declined and new silica gel bags should be replaced. Or the agglomeration of silica gel is heated and dried, so that it can resume the use of sand grains. In the newly purchased wooden boxes of meters, there are often plastic bags for storing silica gel. They should be removed and used for refitting cloth bags. In addition, in the instrument cabinet, it is also equipped with the self incandescent lamp around 100W, or the infrared light around 25W, which is regularly charged (2 to 4h each time), which can also effectively drive the tide of the instrument.






Long term shelved instruments should be draining and drying before use. Usually, the instrument can be placed in a large volume constant temperature box, heating 2 ~ 4H with a temperature of about 60 centigrade. In the absence of a large volume constant temperature box, or when a large amount of hot water is needed, a voltage regulating autotransformer with appropriate electric power can be used to reduce the voltage of the electric power supply to about 190V to make the instrument in a lower power supply. Under the voltage, the electricity is 1 to 2H.






Then increase the voltage of AC power to 220V rating, continue to power 1 to 2h, so that it can also receive moisture and drying effect. Otherwise, during the use of 220V AC power supply, the internal power transformer or the rectifying circuit can jump fire, breakdown or partial short circuit.






In the Huangmei season, if indoor storage instruments and instruments are centralized, doors and windows can be closed, and radiant electric furnaces can be used to raise room temperature to eliminate indoor humidity.






According to the law of climate change, controlling the opening and closing time of doors and windows in meters is an economical way of moisture-proof. Usually, indoor units can be converted to dry and wet bulb thermometers with relative humidity. When indoor humidity is greater than 75%, especially before and after heavy rain, doors and windows should be closed. Generally, the humidity in the morning is large, so it is not advisable to open the windows too early and wait for the fog to disappear. After the sun comes out, it is advisable to open the windows and doors again. When the weather is clear, the doors and windows should be open. Sometimes you can use the sun to drive the tide. But the strong sunshine should be avoided.

  3.heat prevention and heat exhausting

  

  

The electrical strength of the insulating material will decrease with the increase of temperature, and the parameters of the circuit elements are also affected by the temperature (such as carbon resistance and electrolytic capacitor, etc., often due to excessive heat change and damage). In particular, the characteristics of semiconductor devices are significantly affected by temperature, for example, the current amplification coefficient (beta) and the Collector Emitter penetration current (ICeo) of the transistor will increase with the increase of temperature. These conditions will lead to the instability of the instrument. There are even a variety of failures. Therefore, for the "temperature rise" of the instrument. There are certain restrictions, generally not more than 40 degrees, and the highest working temperature of the instrument should not exceed 65 degrees centigrade, that is, not to be limited by the hot hand, usually the indoor temperature is most suitable at 20~25. If the room temperature exceeds 35 degrees C, the artificial cooling measures such as ventilation and heat discharge should be adopted, and the time of the continuous work of the instrument can be shortened properly. When necessary, the cover plate of the casing should be taken to benefit the heat dissipation. However, it should be pointed out that it is forbidden to spray water or place ice blocks in the storage room to prevent moisture from eroding instruments.






Besides, the instrument should be prevented from exposure to sunlight for a long time. So that the paint layer of the instrument shell can be heated, discolored, cracked or even deformed. In particular, the dial of the instrument, often due to long exposure to heat, leads to the cracking or warping of the scale of the scale, resulting in inaccurate reading or even inability to use. So, if there is an East and west window in the place where the instrument is placed or used, the curtains should be put down in the summer, especially in the summer season.

  

  4.Shockproof and anti loose

  

  

Most of the instruments are on the chassis of the shell. It is equipped with rubber cushions for shockproof. If rubber pad is found to be deformed, hardened or shedding, it should be updated at any time.






When handling or moving instruments, they should be handled gently, and no severe vibration or collision should be prohibited, so as to avoid damaging parts such as plug-ins and heads of instruments. In the process of overhauling the instrument, parts such as spring washers, shields of electronic tubes, and spring fasteners should not be omitted. Before handling heavy instruments, you should pay attention to checking whether the handles on the instruments are reliable. For instruments equipped with plastic or artificial leather handles, the base should be handled when handling, so as not to break the instrument and break the instrument.






No percussion and percussion should be done on the table.






No mechanical or electrical equipment should be installed or placed near centralized storage. Attention should be paid to fastening screws for switches, knobs, dials, adapters, etc. The varnish can be added when necessary in order to avoid loosening.






When the new instrument is opened, the original shock proof equipment in the box should be preserved (such as: Wan carton box, foam plastic box, plastic air cushion, paper bar, wood flower, etc.) so as to be used for the reloading of the box.

  

  5.Anticorrosion

  

  

Meters should be kept away from acidic or alkaline objects (such as batteries, lime barrels, etc.). If the battery is installed inside the meter, it should be checked regularly to avoid leakage or decay. If the battery is not used for a long time, remove the battery and store it separately. For the instruments with standard batteries (such as digital DC voltmeter, compensatory voltmeter, etc.), the inversion should be prevented during handling: the standard battery should be removed and transported separately when the container is packed and moved.






If the instrument needs to be stored for a long time, Vaseline or butter should be used to wipe the coating parts of the instrument panel (such as button switch, panel screw, handle, socket, socket, etc.) and metal attachments, and sealed with oil paper or wax paper to avoid corrosion. When used, use dry cloth to wipe the grease on the net.

  

  6.Leakage prevention

  

  

As the instruments mostly use electric power to supply power to power supply, the prevention of leakage is an important maintenance measure which is related to the use of safety, especially for the use of double core power plug. If the shell of the instrument has no grounding or zero, if the primary winding of the internal power transformer inside the instrument is serious leakage between the casing, there may be a considerable AC voltage between the instrument shell and the ground (100 ~ 200V). In this way, when a person touches the instrument shell, he will feel numb electricity and even electrocution. Therefore, the leakage degree of various meters must be checked regularly.






That is, when the meter does not plug in the electric power supply, the power switch of the instrument is pulled to the "pass" position, and then the meter power plug is used to check the insulation between the shell and the shell with the MEG table (the shake table). According to general regulations, the minimum allowable insulation resistance of electrical appliances must not be less than 500K ohm, otherwise it should be prohibited to be used for maintenance or treatment.






If there is no Mega meter, it can also be taken on the condition of the precaution against electricity (such as wearing rubber gloves or operating on rubber pad), connecting the measured instrument to the electric power supply, and using the 250V AC voltage gear of the multimeter to check the leakage degree.

  

  7.Qualitative test

  

  

Before or when the instrument is used, the instrument should be tested qualitatively, that is to check whether the working condition of the instrument equipment is normal or not, so that the problem can be detected and corrected in time.






The qualitative test project should not be too much, the test method should also be simple and reliable, as long as it can determine the main function of the equipment and the function of various switch, knob, dial, head, oscillographic tube and other surface devices. If the electronic voltmeter is qualitatively tested, it is required that the "zero position" of all voltage grades be adjusted to normal and voltage "correct" accurately.

  

  8.Periodic verification

  

  

Because the instrument has a certain life and precision, so the instrument is used for a long time, its main performance will gradually decline, which requires regular verification of the indicators of the main performance of the instrument.

For a general instrument, after a certain period of time (about one year) or a major repair, the main technical data given by the instrument instructions should be compared and calibrated with the aid of standard instruments, instruments, or the same type of new instruments. This is the so-called quantitative test to check whether the performance of the instrument is decreasing.

Precision standard instrument. Such as compensation standard voltmeter, digital frequency meter and so on, continuous working 1000h or storage time of one or two years, it is possible to lose its original accuracy and reliability, must be reported to the provincial and municipal Standards Bureau for "legal verification". The standard precision instrument after statutory verification can be used as a practical standard instrument for instruments with lower accuracy.


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