Page 693 - Industrial Power Engineering and Applications Handbook

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I1 Effect of leakage on
performance:
(i) Operating safety Since the oil is filled at atmospheric pressure, there is Not applicable Not applicable (i) Generally, the use of Generally a safe
generally no leakage SF, is safe, inhaling is equipment. But in the
poisonous. If there is a event of vacuum leakage
leakage it would be which, although remote,
dangerous. SF, itself is may cause a fire hazard
non-toxic, but decom- and X-rays. X-ray
posed SF, is moderately warning and proper
toxic and must be shielding may be
handled under controlled essential
conditions. Training and
guide-lines are essential
for personnel working
on such equipment. Site
data collected from
various sources,
however, suggest a
leakage rate of less than
0.1 % per annum
(ii) Dielectric strength Not applicable Not applicable Not applicable Not applicable Still high Zero
(iii) Intempting capacity Not applicable Not applicable Not applicable Not applicable. But if the In the event of a In the event of a
leakage is in the compres- leakage, the breaker will leakage, the breaker will
sed air supply system, the still be in a position to not be in a position to
breaker may not interrupt interrupt the normal interrupt even normal
on fault, depending upon currents currents
the air pressure the system
is able to maintain on a
leakage
12 Fire hazards Generally, oil is fire hazardous, but not prone to it They may be rated as more fire hazardous than a Arc formation and extinction takes place inside a
unless the dielectric strength reaches a very low BOCB or MOCB in view of arc formation taking sealed chamber, thus emitting no gases or vapoura
level and the medium itself becomes conducting. place in the open, although under controlled conditions. to the atmosphere, which may be a cause of fire
Nevertheless, they are not suitable at locations They are not suitable for installations prone to fire hazard. They are the most appropriate choice for
which are fire hazardous. Normal make or break, hazards, unless the sub-station or the control room such areas
even on fault, may only deteriorate the quality of' where they are installed is isolated from the area of
oil, but yet not make it fire hazardous, unless as hazards (Section 7. I I). They are generally suitable
noted above for all other areas
13 Noise level Quiet operation Quiet operation Except during an Thunderous noise during Quiet operation Quiet operation
interruption, it has quiet an interruption, because of
operation air blast. The intensity can
be controlled by providing
silencers