British Rail Class 302
Encyclopedia
The British Rail Class 302 (pre-TOPS
AM2) was a type of electric multiple unit
(EMU) introduced between 1958 - 1960 for outer suburban passenger services on the London, Tilbury and Southend Railway
route. This class of multiple unit was constructed using the Mark 1 bodyshell and was slam door.
Trailer coaches were originally fitted with Gresley bogie
s which were replaced on Driving Trailer (DT) and Trailer Standard Open (TSO) which was formerly Composite Trailer and B5 Bogies on Battery Driving Trailer which became Battery Composite Trailer, the refurbishment moved First class accommodation to a position over the Westinghouse CM38 main compressor which was noisy and caused vibration. The Motor Coach retained its Gresley derived bogies after refurbishment.
The Battery Driving Trailer and Driving Trailer were fitted with drop head buckeye couplers with screw coupler in the Guards Van, retractable Buffers are also fitted only on outer ends of the Battery Driving Trailer/Driving Trailer.
Originally the vehicles were insulated with "Blue" asbestos
which was removed and sealed during refurbishments.
Unit 302 244 was involved in an accident with a lorry at a level crossing
at Low Street railway station
in Tilbury, after which it was decided to scrap the leading carriage. This was replaced with a carriage originally belonging to a Manchester-Bury Line Class 504
.
Following the privatisation
of British Rail
, the units passed to LTS Rail in 1996.
The class was fully withdrawn from service in 1999 due to the age of the units, with some being 40 years old. They were replaced by Class 310
units, Class 312
units, and Class 317
units, the latter of which were on loan from WAGN.
with the majority of equipment being interchangeable with Class 308 units.
Electrically there were 3 main systems, Control which operated at 110 volt
s DC
, provided by nickel iron alkaline Secondary cells
, auxiliary 250 Volts AC
from the tertiary winding of the main transformer
which provided power to battery charger which also rectified to power main compressor
, and finally power circuits derived from secondary winding of the main transformer at 1,500 Volts AC.
The primary winding of the transformer was designed to operate on either 6.25 kV
or 25 kV with voltage sensing equipment fitted to ensure the correct arrangement of primary windings for a given voltage. An incorrect voltage selection device was fitted to both the Class 302 and Class 308
stock so that if the primary winding was connected for 6.25 kV when supplied with 25 kV the Air Blast Circuit Breaker
(ABB) manufactured by ABB Asea Brown Boveri would remain closed but the pantograph would be lowered. Should this happen the transformer would require changing and overhaul as well as possibly other equipment due to flashover
damage.
The transformer was also protected by a Buchholz relay
which monitored any gas build-up within the cooling/insulating oil, as the acetylene
(ethyne) gas generated is highly explosive. All Class 302 and 308 stock were fitted with Stone Faiveley pantograph
s for current collection from the overhead line. A particular oddity of Eastern/Anglian region EMU stock was the fitting of fibre glass
snow shields between the pantograph and the supporting insulators.
One member of the class, 302 302, was experimentally fitted with thyristor
control in the early 1970s. After the experiment it was converted back to the original tap changer control, although the guard's van remained slightly different internally.
, Essex
. These units have been repainted into BR overall blue with yellow ends and are still in very good condition with the destination scrolls still in working order, the seats still in British Rail colours, and the Network South East maps still in very good condition. The rest of the fleet has been scrapped since withdrawal in late 1999.
TOPS
Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...
AM2) was a type of electric multiple unit
Electric multiple unit
An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...
(EMU) introduced between 1958 - 1960 for outer suburban passenger services on the London, Tilbury and Southend Railway
London, Tilbury and Southend Railway
The London, Tilbury and Southend Railway is an English railway line linking Fenchurch Street railway station in the City of London with northeast London and the entire length of the northern Thames Gateway area of southern Essex. It is currently known as the Essex Thameside Route by Network Rail...
route. This class of multiple unit was constructed using the Mark 1 bodyshell and was slam door.
Service History
Each unit was formed of four coaches in the formation BDTS - MBS - TC - DTS.Trailer coaches were originally fitted with Gresley bogie
Bogie
A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...
s which were replaced on Driving Trailer (DT) and Trailer Standard Open (TSO) which was formerly Composite Trailer and B5 Bogies on Battery Driving Trailer which became Battery Composite Trailer, the refurbishment moved First class accommodation to a position over the Westinghouse CM38 main compressor which was noisy and caused vibration. The Motor Coach retained its Gresley derived bogies after refurbishment.
The Battery Driving Trailer and Driving Trailer were fitted with drop head buckeye couplers with screw coupler in the Guards Van, retractable Buffers are also fitted only on outer ends of the Battery Driving Trailer/Driving Trailer.
Originally the vehicles were insulated with "Blue" asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...
which was removed and sealed during refurbishments.
Unit 302 244 was involved in an accident with a lorry at a level crossing
Level crossing
A level crossing occurs where a railway line is intersected by a road or path onone level, without recourse to a bridge or tunnel. It is a type of at-grade intersection. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion...
at Low Street railway station
Low Street railway station
Low Street Station was a station on the London, Tilbury & Southend line. The station opened in 1861, at a level crossing. It served the small villages of West and East Tilbury. The station closed in 1967.-References:...
in Tilbury, after which it was decided to scrap the leading carriage. This was replaced with a carriage originally belonging to a Manchester-Bury Line Class 504
British Rail Class 504
The British Rail Class 504 was a unique type of electric multiple unit that ran on 1200 V DC third rail with side-contact current collection. All other UK third rail has the electric "shoe" on top of the rail. The type was used only between Manchester and Bury...
.
Following the privatisation
Privatisation of British Rail
The privatisation of British Rail was set in motion when the Conservative government enacted, on 19 January 1993, the British Coal and British Rail Act 1993 . This enabled the relevant Secretary of State to issue directions to the relevant Board...
of British Rail
British Rail
British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...
, the units passed to LTS Rail in 1996.
The class was fully withdrawn from service in 1999 due to the age of the units, with some being 40 years old. They were replaced by Class 310
British Rail Class 310
The British Rail Class 310 is a slam-door, alternating current electric multiple unit introduced in 1963 as part of the West Coast Main Line electrification project. They were initially classified as Class AM10 units before the introduction of the TOPS classification system. Constructed at BR's...
units, Class 312
British Rail Class 312
The British Rail Class 312 is a type of alternating current electric multiple unit built in 1975-1978 for use on outer-suburban passenger services. It was the last class of multiple unit to be constructed with the British Rail Mark 2 bodyshell, and also the last with slam doors...
units, and Class 317
British Rail Class 317
The British Rail Class 317 alternating current electric multiple units were built by BREL York in two batches, from 1981-82 and 1985-87. They were the first of several classes of British Rail EMU to be based on the all-steel Mark 3 bodyshell, departing from the "PEP"-aluminium design which had...
units, the latter of which were on loan from WAGN.
Electrical Equipment
Electrical equipment was supplied by English ElectricEnglish Electric
English Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...
with the majority of equipment being interchangeable with Class 308 units.
Electrically there were 3 main systems, Control which operated at 110 volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
s DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
, provided by nickel iron alkaline Secondary cells
Nickel-iron battery
The nickel–iron battery is a storage battery having a nickel oxide-hydroxide cathode and an iron anode, with an electrolyte of potassium hydroxide. The active materials are held in nickel-plated steel tubes or perforated pockets...
, auxiliary 250 Volts AC
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
from the tertiary winding of the main transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
which provided power to battery charger which also rectified to power main compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
, and finally power circuits derived from secondary winding of the main transformer at 1,500 Volts AC.
The primary winding of the transformer was designed to operate on either 6.25 kV
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
or 25 kV with voltage sensing equipment fitted to ensure the correct arrangement of primary windings for a given voltage. An incorrect voltage selection device was fitted to both the Class 302 and Class 308
British Rail Class 308
The British Rail Class 308 alternating current electric multiple units were built by BR at York, in three batches, from 1959–61. They were initially classified as AM8 units before the introduction of TOPS.-Class 308/1:...
stock so that if the primary winding was connected for 6.25 kV when supplied with 25 kV the Air Blast Circuit Breaker
Circuit breaker
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow...
(ABB) manufactured by ABB Asea Brown Boveri would remain closed but the pantograph would be lowered. Should this happen the transformer would require changing and overhaul as well as possibly other equipment due to flashover
Flashover
A flashover is the near simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated they undergo thermal decomposition and release flammable gases...
damage.
The transformer was also protected by a Buchholz relay
Buchholz relay
In the field of electric power distribution and transmission, a Buchholz relay is a safety device mounted on some oil-filled power transformers and reactors, equipped with an external overhead oil reservoir called a conservator...
which monitored any gas build-up within the cooling/insulating oil, as the acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
(ethyne) gas generated is highly explosive. All Class 302 and 308 stock were fitted with Stone Faiveley pantograph
Pantograph (rail)
A pantograph for rail lines is a hinged electric-rod device that collects electric current from overhead lines for electric trains or trams. The pantograph typically connects to a one-wire line, with the track acting as the ground wire...
s for current collection from the overhead line. A particular oddity of Eastern/Anglian region EMU stock was the fitting of fibre glass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
snow shields between the pantograph and the supporting insulators.
One member of the class, 302 302, was experimentally fitted with thyristor
Thyristor
A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased .Some sources define silicon controlled rectifiers and...
control in the early 1970s. After the experiment it was converted back to the original tap changer control, although the guard's van remained slightly different internally.
Preservation
Two driving trailers No. 75033 and No. 75250 carriages which belonged to units 302 201 and 302 277 are preserved at Mangapps Farm Railway Museum near Burnham-on-CrouchBurnham-on-Crouch
Burnham-on-Crouch is a town in the Maldon district of Essex in the East of England. It lies on the north bank of the River Crouch.-History:Historically, it has benefited from its location on the coast - first as a ferry port, later as a fishing port known for its oyster beds, and most recently as a...
, Essex
Essex
Essex is a ceremonial and non-metropolitan county in the East region of England, and one of the home counties. It is located to the northeast of Greater London. It borders with Cambridgeshire and Suffolk to the north, Hertfordshire to the west, Kent to the South and London to the south west...
. These units have been repainted into BR overall blue with yellow ends and are still in very good condition with the destination scrolls still in working order, the seats still in British Rail colours, and the Network South East maps still in very good condition. The rest of the fleet has been scrapped since withdrawal in late 1999.
External links
- Class 302 general overview on Class 310 site
- BW Photo of unit no. 298 at Barking c. 1964
- The Railway Centre data page on the Class 302