Mercury Arc rectifier

A mercury-arc rectifier in use - Laxey substation on the Manx Electric Railway, Isle of Man.

The substation was built in 1935, and as far as I can tell this rectifier, made by the Hackbridge-Hewettic company, was installed at that time. From what I have been able to find out (sources of information appear to be limited!) there are two 200kW rectifiers here. The supply to the substation is 6,600V AC, the output is 550V DC and it supplies the Manx Electric Railway main line, along with other substations at Groudle and Ballaglass. Photos of the rest of the substation can be found at http://lucking.org/i/156793 (pages 2 and 3).

At the time of filming in June 2004, another pair of mercury arc rectifiers at Bungalow substation on the Snaefell Mountain Railway had just been taken out of use - there was still an unused spare rectifier bulb in a packing case! They were 150kW examples, and photos of them can be seen at http://lucking.org/i/156579 .

As far as I am aware, the mercury arc rectifiers at Laxey are still in daily use.

The basic principle behind the operation of a mercury-arc rectifier is that the mercury vapour will only conduct electricity in one direction - the pool of mercury at the bottom is the cathode (connected to the DC output), and the anodes (connected to the transformer windings) are in the 'arms'.

More about Mercury Arc rectifiers:
http://www.tigercom.dsl.pipex.com/whatis.htm
http://en.wikipedia.org/wiki/Mercury_arc_valve

The third image on this page is a very good circuit diagram explaining how (and why!)mercury-arc rectifiers work.

http://www.electricstuff.co.uk/mercarc.html

Category:

Autos & Vehicles

Tags:

• mercury
• arc
• rectifier
• glass
• bulb
• Laxey
• Isle
• of
• Man
• IOM
• MER
• Manx
• Electric
• Railway
• substation
• Hewettic

[thexrealxASK1]

? what is its purpose ? reply me .

[bodnet]

It converts AC (Alternating Current) electricity into DC (Direct Current) electricity. Since the 1960s diodes have been used to do this in much smaller installations....

[peterban1234]

It looks like an alien brain calculating how much is 1+1.

[jizzmonger]

Enough to make fillings for all of New York's hobos.

[rsp196607]

We would also like to see at least stiil photos of the ones that were used at the two coverter stations of the Pacific DC Intertie prior to their replacement by thyristors.

[rsp196607]

ABB

[avenged06x]

Asea Brown Boveri

[ericperic66]

@oracle2world Actually, one of these did appear in at least one Frankenstein film. The company that made them had a demonstration rig which used to sit on their stand at the Electrical Engineering Exhibition back in the 50's/60's and this was used at least once in a film. The factory was quite near to Shepperton Studios and also Walton Studio.

[rsp196607]

How much power is that thing dissipating?

[oracle2world]

How come these never appeared in Frankenstein films and the such? Great audio and video presentation. I mean, if you want a mad scientist ambience.

[fartingvicar]

Brilliant, I have not seen one of these working since I worked as an Electrician for London Country Buses / Green Line Coaches (formerly London Transport). Every garage used to have one of these (some had two) and they were used as as battery chargers. We could charge many batteries at the same time and could adjust the output voltage and current independently .

When we used to have have groups of school children visit the garage, I use to fire it up. It is now in the LT Depot Museum in Acton.

[SteveTheCart]

@bodnet It does not convert DC into AC; it converts good into evil. Only the devil himself could design something so beautiful.

[DutchFord86]

I still have 6 of these in service. 700 KW each. Made by Brown Boveri in 1964 powering the DC engines of a steel rolling mill.

[Amoorsable]

talk about out dated technology...its old school