Corona extension gauge

Corona extension gauge includes the level bar of contrast measurement corona width and the perpendicular chi of contrast measurement corona height, perpendicular chi is rectangular form with the level bar, and perpendicular chi intersects vertically in the central authorities of level bar with the level bar, be equipped with the first measurement zone, second measurement zone, the third measurement zone that are used for the contrast to measure the corona width on the level bar, different and the central authorities that all use the level bar of the width of first, second, third measurement zone are central symmetry, the both ends homogeneous phase of first, second, third measurement zone is answered is equipped with the perpendicular groove that shows the measurement zone limit, the lower extreme of perpendicular chi is equipped with as tooth incisxal edge base reference of reference cross slot, the upper end of perpendicular chi is equipped with and is used for contrasting first cross slot, second cross slo