Verification and Adjustment Methods of Electric Contact Pressure Gauges

Ⅰ. Main technical indexes of electric contact pressure gauges

Technical index requirements shall be met after instrument calibration, and following items are the main technical indexes of this pressure gauge

Basic errors: Errors caused by the material of the spring tube and the defects of the pressure gauge and do not exceed its maximum permissible error. The maximum permissible error is known from the nominal accuracy grade.

Hysteresis error: Errors caused by elastic hysteresis and elastic aftereffect of elastic materials. Does not exceed its maximum permissible error.

Friction error: Display error caused by gear clearance. Does not exceed 1/2 of its maximum permissible error.

Ⅱ. Adjustment of electric contact pressure gauges

Electric contact pressure gauges shall be adjusted as follow if quality does not meet the standards after instrument adjustment.

1. Ratio error

If the indicating value of electric contact pressure gauges shall be increased proportionally, the regulating screw can be slightly moved outward to increase the cleat value. On the contrary, move the regulating screw inward slight. After completing the adjustment, make the screw tightened.

2. Nonlinear errors

Rotating baseboard of the electric contact pressure gauge: when the indicating value is large at front end and small in the rear end, rotate the baseboard counterclockwise to reduce the included angle of rod and sector gear; on the contrary, rotate the baseboard clockwise to increase the included angle of rod and sector gear.

Adjusting rod of the electric contact pressure gauge: For the instrument with adjustable rod length, when the rod length is increased, the included angle between the rod and the sector gear can be reduced, so as to adjust the non-uniformity of the electric contact pressure gauge expression value, which is large at the front end and small at rear end. On the contrary, the included angle is enlarged, and the adjustment instrument represents the unevenness of the value from small to large.

Hairspring torque adjustment of the electric contact gauge: hairspring's degree of tightness directly affect the pointer back to zero and to the upper limit as well as the nonlinear errors and friction errors. If the pointer does not back to the zero and indicating value large at front end and small at rear end and the error is small, separate the occlusive central gear and sector gear and rotate small axle to loosen or tight the hairspring.

Ⅲ. Certain large errors of electric contact pressure gauges

When the error of indicating value is only one or two points beyond the allowed range, the pinion can be moved forward or backward to change the occluding position and make the sector gear and pinion occluding evenly.

Ⅳ. Electric calibration of electric contact pressure gauges

1. Install the pressure gauge on the tester, set the upper limit and lower limit signal contact pointer at more than 3 different test points, and slowly increase or decrease the pressure until the signal instantaneous. The deviation between the reading of the standard meter and the value indicated by the signal pointer should not be greater than the absolute value of the permissible basic error.

2. The main failure phenomena, causes and treatment methods of the electrical calibration process of the electrical contact pressure gauge are as follows.

(1) Symptom: The electric contact pressure gauge signals prematurely or late. Cause: Contact position is incorrect or contact metal rod is loose. Treatment: vertical contact correction until appropriate signal generation; Tighten the contact metal rod to make it firm. If it is light, the hairspring can be properly enlarged to increase the hairspring counter-torque.

(2) Symptom: No signal occurs on the electric contact pressure gauge. Cause: contact is too dirty, poor contact; Damp insulation layer of signal device; The circuit is blocked. Treatment: contact is too dirty, use sandpaper to polish dirt; The insulation layer is dried by hot air when damp; If the circuit is blocked, the cause of the break should be found and repaired.