Kawasaki Heavy Industries & Nippon Sharyo C751B


The Kawasaki Heavy Industries & Nippon Sharyo C751B, sometimes abbreviated to C751B or KNS C751B is the third generation electric multiple unit rolling stock in operation on the North South and East West Lines of Singapore's Mass Rapid Transit system since early 2000. 21 trainsets of 6 cars each were purchased at S$231 million, and it is the first rolling stock to feature VVVF insulated-gate bipolar transistor traction control system. Kawasaki Heavy Industries manufactured 66 cars and Nippon Sharyo manufactured 60 cars respectively with no comparable differences, having built to agreed specifications. These trains are the third generation of rolling stock to be used on the two lines. All 21 of these trains are permanently operating on the East West Line, with occasional appearances on the North South Line.

Design

Exterior design

The front of the train sports a more slanted and streamlined look, with the run number display in Orange LED Display. The C751B train is the first train to have the updated SMRT livery that ran between 1999 and 2014.
These trains were fitted with Mobitec MobiLED electronic destination displays for train run numbers. The C751B was also the first MRT train type to feature anti-climbers, which help prevent overriding of the train cab in the event of a collision that could cause a catastrophic failure. They also feature rubber guards to prevent people from falling between cars: this feature was also used on the C151A. The C151A, C151B and C151C trainsets are also derived from the C751B.

Interior design

All cars have been retrofitted with 6 LCD displays per car, and all except trainset 347/348 which features VPIS displays from July 2001 to September 2009. These used to show rail travel information, commercials and movie trailers. The C751B is also the first train to have wheelchair space, with the retrofitting of the elevators in the MRT stations began in 2000. The interior design was also improved; the seats were now 48 cm wide - about 5 cm wider than on previous train types.
The LCD screens were deactivated since July 2007 and LED displays was not used since January 2008 with the change of voice announcer. All VPIS were removed to make way for the STARIS by 2010. In 2013, support bars are added to the seats with hand grips, and the middle handrails with hand grips are configured to join across nearly one carriage, as such all triplicates stanchion poles are replaced by regular single grabpoles.
The colour layout on these trains are also different from their earlier counterparts. Cars 1 and 6 use a sort of pinkish-purple color on the seats, while cars 2 and 5 use a different shade of blue, and the middle cars using a bluish-green. All door panels and walls are white, which is a standard appearance of all SMRT trains.

Equipment

Main Propulsion Controller/Motor

The C751B is the second commuter type Electric Multiple Unit after the Sanyo 5030 series to feature electric systems fully manufactured by Fuji Electric. Propulsion is controlled by VVVF Inverter with 2-level IGBT semiconductor controller, rated at 415 kVA. Each inverter unit controls two motors on one bogie, and one motor car features two of such units. Motors are three-phrase AC induction type, model MLR109, with a maximum output of 140 kW.

Bogies

The C751B uses the monolink axlebox type bolsterless air spring bogie. There are no major technical difference between a trailer and motor car bogie other than additional electrical components for the latter.

Auxiliary Systems

A break from tradition, the C751B features auxiliary inverters for its electrical systems on all six cars of the train. Previously, auxiliary inverters are mounted only on motor cars. The VVVF Inverter is controlled by IGBT semiconductors and rated at 80 kVA. A battery charger is built with the inverter and provides 16 kW output.

Experimental programmes

In 2001, when the Changi Airport Line was opened, some of these trains plying the East West Line had luggage racks installed. These luggage racks were installed in every carriage of the train, taking up the space of two seats next to the door at the end of each carriage. The purpose of those racks were to let travellers heading to the airport, who usually carry a large amount of luggage, to have a space to place their bags easily.
However, these luggage racks were always underutilised. Travellers preferred holding on to their bags where they were standing or sitting, as opposed to placing them on the luggage racks, probably due to convenience and fear of theft. Some commuters were also complaining that these racks took up critically needed space which could be occupied by other passengers which often filled the train. Furthermore, the service to Changi Airport was cancelled and replaced by a shuttle service to and from Tanah Merah station, dismissing the need to provide these racks for non-airport bound train services. Therefore, in 2003, trains with the luggage racks had them removed, and replaced with an empty standing area, with a dual purpose of serving as a wheelchair area.
Energy efficient LED lights are on trial in train car 1328 and 3328.
STARIS Version 2.0 was installed on train car 3322 in 2010 but it was uninstalled in 2016.

Operational incidents

Train withdrawal incidents

On 13 April 2002, a fault was detected in a C751B train and it was subsequently withdrawn to Changi Depot for investigations. As the train was under warranty, the engineers from the manufacturers of the train and gearbox were flown in on 21 April. They subsequently detected metal fragments in the gearboxes, and those of another 20 trains. On 23 April 2002, SMRT immediately withdrew all 21 C751B trains and suspended the Boon Lay – Changi Airport train through service, replacing it with the Tanah Merah – Changi Airport shuttle service. Train frequencies were also adjusted until 6 May 2002, when 8 trains returned to service. Service resumed on 16 May 2002, with 7 more trains back on service. By end of May 2002, all C751B trains had been returned to service.

Incident of vandalised train

On 17 August 2011, a security breach occurred at Bishan Depot in which C751B set 311/312 was vandalised by 2 Americans named Jim Harper and Danielle Bremner. The graffiti was noticed only after the train had been in service for several hours. SMRT was eventually fined $200,000 by the Land Transport Authority.

Train Formation

The configuration of a C751B in revenue service is DT-M1-M2-M2-M1-DT
The car numbers of the trains range from x311 to x352, where x depends on the carriage type. Individual cars are assigned a 4 digit serial number by the rail operator SMRT Trains. A complete six-car trainset consists of an identical twin set of one driving trailer and two motor cars permanently coupled together. For example, set 345/346 consists of carriages 3345, 1345, 2345, 2346, 1346 and 3346
The reason why they used 311/312 instead of 301/302 is because of the Money train on Kawasaki Heavy Industries C151 whose car numbers are 301/302 but they were sold to Singapore Armed Forces.