IEC 60970 Insulating liquids - Methods for counting and sizing particles
3 General caution, health, safety and environmental protection
This International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of the standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use.
The insulating liquids which are the subject of this standard should be handled with due regard to personal hygiene. Direct contact with the eyes may cause irritation. In the case of eye contact, irrigation with copious quantities of clean running water should be carried out and medical advice sought. Some of the tests specified in this standard involve the use of processes that could lead to a hazardous situation. Attention is drawn to the relevant standard for guidance.
This standard is applicable to insulating liquids and used sample containers, the disposal or decontamination of which must be done according to local regulations. Every precaution should be taken to prevent release of mineral oil into the environment.
4 Significance
It is well known that particles have a detrimental effect on the dielectric strength of insulating liquids. It has long been the practice to include in specifications of insulating liquids the requirement that the fluid be clear and free of visible particulate matter. However, there has been no standard method for quantitative estimates, so that practices have differed. This standard gives standard procedures for the test.
Filtration of insulating liquids is an established practice in the electrical industry. The procedure described may serve to assess the performance of the filter system. The results obtained are dependent upon the method used. With the automatic counter the measured values also depend on the calibration procedure and in particular on the calibration material. It is therefore essential that the methods of analysis and the calibration standards are specified when quoting results.
The particle content of a sample may depend on different transformer parameters as well as the condition of the oil itself.
Storage may affect the sample, due to sedimentation and/or coalescence of particles. Shaking of the sample before analysis will be necessary.
