Measurement of ash density of insulator surface contamination

1. Definition of ash density: The total mass of insoluble substances in the dirt on the surface of the insulator divided by the surface area. Unit: mg/cm2.

2. Steps for measuring ash density: (Take HM-3000 ash density tester as an example)

(a) Dissolution. Dissolve the dirt on the surface of the insulator in a certain volume of distilled water. The volume of distilled water is approximately the surface area of ​​the insulator (unit: cm2) * 0.2ml. For example: if the surface area of ​​the insulator is 1450 cm2, the volume of distilled water should be about 290ml. When the salt content in the dirt is high, the amount of water can be increased as appropriate.

(b) Filtration. There are two methods of filtration, one is conventional filtration and the other is filtration using a vacuum filtration device. Conventional filtration has simple experimental conditions and is easy to operate, but the filtration speed is slow. The advantage of using a vacuum filtration device for filtration is that the filtration speed is fast, but the price of the experimental equipment is higher.

(c) Drying. Fold the filtered filter paper pair at 90 degrees and put it into a constant temperature drying oven for drying. When the drying temperature is set to 90°C, dry for 30 minutes. It is best to dry completely.

(d) Weighing. Weigh the weight of the filter paper before filtration, which is counted as Mf; weigh the dried filter paper with ash, which is counted as Ms.

(e) Calculation. The ash density on the surface of the insulator NSDD = (Ms-Mf)/S. Unit: mg/cm2.

3. Precautions during measurement

(a) It is recommended to use a special gauze towel to wipe the dirt on the insulator, or test paper can be used instead. The basic requirement is that the gauze towel, filter paper, etc. used for wiping do not contain soluble substances. Otherwise, the measurement result will be smaller.

(b) When using a balance, the base of the balance should be adjusted to a horizontal position first. Do not touch the calibration weights and tray of the balance directly with your hands.

(c) The drying temperature cannot be set too high, generally not exceeding 110°C, otherwise it may cause the filter paper to burn. (end)