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).
And ordering two specific Osram rectifying valves for high tension D.C. insulation tests.
| Identifier | ExFiles\Box 41\2\ Scan038 | |
| Date | 8th December 1926 | |
| To Wd.{Mr Wood/Mr Whitehead} from EFC. X3646 EFC1/T8.12.26. RECTIFYING VALVE FOR H.T. D.C. INSULATION TESTS. Reference your Wd{Mr Wood/Mr Whitehead}11/NJ29.11.26, we have considered this matter and made some tests, and we have decided from these tests that it is unnecessary to have an expensive valve such as the one quoted for the purposes of these H.T. insulation tests in which no rectified current has is actually delivered (except a small leak effect). Our requirements, therefore, are now decided to be :- One type U.3 high voltage power rectifying valve, List Price £1.8.0. One type U.4 low voltage power rectifying valve, List Price 15/-. The former valve is to be used for experimental high tension D.C. tests in connection with our H.T. transformer, the combination being the equivalent for testing purposes of the large Wimshurst machine. The latter valve is for a similar purpose, but where the H.T. is supplied, not by a H.T. transformer, but by a trembler coil, and is for use in developing an apparatus which can be used by the Production Dept. in the H.T. leakage testing of moulded coil cases to ensure that no faulty coil cases are used. We have already made tests of this nature and proved that on some of the old coil cases which are known to be faulty, a considerable leak effect can be shewn in this manner. We shall be pleased therefore, if you will place an order for one each of these two Osram rectifying valves, types U3. and U4. EFC. | ||