Use, selection and pre use inspection of clamp Ammeter
1. Purpose: It can measure AC current on low-voltage lines without interrupting load operation (continuously opening current carrying wires). (Below 50HZ and 500V)
2. Selection: Its accuracy and maximum range should meet the testing needs.
3. Pre use inspection:
(1) Appearance inspection: All parts should be intact; The clamp handle should be flexible; The iron core of the jaw should be free of rust and tightly closed; The insulation sheath of the iron core should be intact; The pointer should be able to swing freely; Gear changes should be flexible and sensitive to the hand;
(2) Adjustment: Place the instrument horizontally with the pointer pointing towards the zero position, otherwise adjust to the zero position.
measure
1. Select the appropriate gear. The principle of gear selection is: (1) When the measurement current range is known, select a gear that is greater than the measurement value but close to the measurement value.
(2) When the current range to be measured is unknown: it can be placed in the current test first (or according to the cross section of the wire, and its safe current carrying capacity is estimated, appropriately selected), and whether the downshift measurement needs to be determined based on the test situation. In short, the deflection angle of the hand should be as large as possible.
2. Testers should wear gloves, flatten the end of the instrument, open the jaws, and close the jaws after the tested wire enters the jaws.
3. The tested wire should be located in the center of the jaw space, and the jaw should be tightly closed;
4. After measuring large current and before measuring small current, the jaws should be opened and closed several times for demagnetization;
5. When measuring small current, if the deviation angle of the needle is still very small during gear measurement (the deviation angle of the needle is very small, which means that the relative error of its measurement is relatively large), it is allowed to wind the wire several times on the jaw iron core, and close the jaw to read the reading. At this point, the current value on the wire=reading ÷ number of turns (turns calculation: how many wires are in the clamp, calculated based on how many turns);
6. Reading: Based on the gear used, take a reading on the corresponding scale line. (Attention! The gear value is the full offset value);
After use, the gear should be set to current.
Safety issues to be noted in measurement
1. Thoroughly inspect the instrument before measurement and select the correct file;
2. Wear gloves (insulated gloves or clean and dry wire gloves) during testing, and set up monitoring if necessary;
3. When gear shifting measurement is required, the wire should be extracted from the jaws first, and then clamped in for measurement after gear shifting;
4. Do not measure the current on bare conductors;
5. When measuring, pay attention to maintaining a safe distance (not less than 0.1 meters) from nearby charged objects, and be careful not to cause phase to phase short circuits or phase to ground short circuits to prevent personal shock from electric shock;
6. It is not allowed to measure on the moving contacts or fuses of the switch;
7. After use, the gear should be adjusted to current. If there is a meter cover, it should be placed inside the cover and stored in a dry, dust-free, non corrosive gas, and vibration free place.
