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).
Informational leaflet for the 'POL' Permanent Mercury Fuse, explaining its time lag and resettable features.
| Identifier | ExFiles\Box 61b\2\ scan0271 | |
| Date | 30th October 1935 guessed | |
| The Reasons WHY Irritating SHORT CIRCUITS and OVERLOADS can be overcome by the “POL” Permanent Fuse Incorporation of Mercury in Fuse construction is an ideal at which numerous manufacturers have aimed. The “POL” has obtained this objective, namely, TIME LAG. The Fuse, as we know it to-day, depends on the carrying capacity of its wire, which, when loaded to its stated value, will burn out in approximately 60 seconds, thus breaking the whole circuit. In the case of a small overload or slight short, the “POL” Mercury Fuse will not blow at stated capacity until a period of 10 to 15 mins. has elapsed. At the same time, when subjected to any definite overload will blow immediately but will not be permanently destroyed— A SLIGHT TAP WILL RENEW THE BREAK IN THE MERCURY; this function will operate for an INDEFINITE PERIOD. LIGHT'S OUT! NO! Just a Slight Tap and then carry on BE CERTAIN—Carry a “POL” Permanent Fuse PRICE 1/6 EACH | ||