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Object numberCHREM:2013.4
Object categoryindustry equipment
Object name"Hewittic rectifier" Mercury arc rectifier unit, glass bulb type, with power supply in metal cabinet
Description"Hewittic rectifier" Mercury arc rectifier unit, glass bulb type, with power supply in metal cabinet, serial number 23I3I (capital i, NOT number 1). From AC to DC - Mercury arc rectifiers were developed in the 1930s to provide direct current (DC) from a mains supply of alternating current (AC). Alternating current could be distributed over a wider area with less energy loss than direct current so it became the power system of choice for electricity networks worldwide as they developed in the period after the first world war. The remaining users of DC preferred it for their electric motors, because DC motor speeds could be controlled more accurately than AC motors until the 1960s. Rectifiers like this are vessels, often made of glass, with a pool of mercury at the bottom. Alternating current passes through the vapour of the mercury and leaves the machine as DC. Mercury arc rectifiers were easier to maintain than rotary converters which were another way of doing the same job. Once installed, they could function for a long time with little attention as long as they were kept between 10 and 30 degrees Celsius. They were usually placed in cabinets containing fans to keep them cool. Mercury arc rectifiers could also be remotely controlled. Among the last users of DC on a large scale was British Rail, which took power from the AC network to feed its DC locomotives
Production date 1940-01-01 - 1949-12-31
Persons keywordHewittic Electric Co Ltd, British Rail
Dimensions
- Height: 3700 mm
Width: 2400 mm
Depth: 1800 mm