Standard test conditions: temperature 20 ℃, humidity 70%, if there is no difference in the test results, you can also test under normal temperature and humidity. Current sensitivity: the scale range of the pointer is from zero to the maximum scale (full scale position), and the sensitivity is 960ua ± 8%. Internal impedance: 650ohm±10%. Insulation resistance: 500V DC of case and circuit plus 50m ohm or higher. Zero position: use the default position of the inst ent. The point where the front end of the pointer coincides with the center of the zero scale is the reference pointer and zero overlap scale. The tolerance is ± 1 mm. Balance: when the default position is tilted forward and backward by 90 degrees, the allowable error range of the inst ent is ± 1 mm. Pointer sticking: when the full scale current instantly triples the over-current and slowly reduces the current reading sensitivity from 1/2, the pointer return to 1/3 of the scale. Friction: when the current is applied to the inst ent and slowly increases or decreases to a certain value, the error range of the indication point is ± 1 mm. Pointer swing direction:from left to right Needle length:44 ± 1 mm from the center line to of the needle Pointer width:0.45 ± 0.05 mm Use direction of meter:vertical Operating temperature range:- 10 ℃ to + 60 ℃ RH 35 to 85% Storage temperature limit:- 20 ℃ to + 60 ℃ RH 35 to 85% Do not place the inst ent in direct sunlight, and store the inst ent in the package to avoid entering the inst ent. The welding conditions place the terminals in a tinplate of about 3 mm at 230 ° C for 3.5 seconds and remain normal after this test. Soldering temperature:keep the soldering iron temperature at 350 ℃, contact with the terminal for 3.5 seconds, and contact the front end of the terminal with the soldering iron about 3 mm. The test remained normal. Anti static:test the dry nylon cloth on the of the