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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
High-tension test report comparing the dielectric strength of coil case materials: redmanol, stabalite, and mouldensite.

Identifier  ExFiles\Box 69\1\  scan0032
Date  7th June 1926
  
EFC.
WB.{Mr Brazier/Mr Bell}92.
X2099 X8710
7.6.26.

H.T. TEST OF COIL CASE MATERIAL. X.2494. X.4079.

We have tested on the H.T. transformer two coil cases side by side, one of redmanol and the other of stabalite material.

It was found that the redmanol case punctured after 2 mins. at a voltage of 22,800. The stabalite case however remained O.K. after 5 mins. at 26,800 v (i.e. the high voltage available).

A few discs .125" thick made of redmanol and mouldensite were also tested and the results were as follows :-

Brown redmanol disc. - remained O.K. after 5 mins. at 27,000 volts.
Black redmanol disc - punctured after 1 min. at 27000 volts.
Brown mouldensite disc - punctured after 1 min. at 27,000 volts.
Black mouldensite disc- remained O.K. after 5 mins. at 27000 volts.

From these results it appears that there is little difference in the dielectric strength of redmanol as compared with mouldensite, but stabalite appears distinctly better.

EFC/H.E.West.
  
  


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