Parts of Electric Locomotive
The diagram (Fig.2.2) shows an AC electric locomotive, i. e., a locomotive collecting AC power from overhead line. The current passes directly from the pantograph (or shoe) to the main and auxiliary inverters.
Almost every part of the modern locomotive equipment uses electronic control. They are usually collected in a control cubicle near the cab for easy access. The controls usually include a maintenance management system which can be used to download data to a portable or hand-held computer.
The traction motor drives the axle through a reduction gear of a range between 3 to 1 (freight) and 4 to 1 (passenger).
Modern traction motors use three phase AC electrical supply and this favoured design can be used on DC and AC electrified railways and electric locomotives, which are equipped with suitable control electronics.
The means by which the power supply circuit is completed with the substation once power has been drawn on the locomotive. Current collected from the overhead line or third rail is returned via the axle brush and one of the running rails.
All trains are provided with a battery for start-up current and for supplying essential circuits, such as emergency lighting in the case of the line supply fails. The battery is usually connected across the DC control supply circuit.
An electric train is almost always provided with some sort of circuit breaker to isolate the power supply when there is a fault, or for maintenance. On AC systems they are usually on the roof near the pantograph. There are two types—the air blast circuit breaker and the vacuum circuit breaker (VCB). The air or vacuum part is used to extinguish the arc when two tips of the circuit breaker open.
当发生故障或者维修时，电力机车几乎都用断路器隔离电力供应。在交流系统中， 断路器通常设在受电弓附近的车顶上。断路器有两种类型：压缩空气断路器和真空断路 器。空气或真空部分用于断路器两个触点分开时灭弧。
Converter is a generic term for any solid state electronic system for converting alternating current to direct current or vice versa. Where an AC supply has to be converted to DC it is called a rectifier and where DC is converted to AC it is called an inverter. The word originated in the US but is now common elsewhere.
转换器是指将交流电变为直流电或者反之的任何固态电气系统的通用术语。将交流 电变为直流电的叫整流器，将直流电变为交流电的叫逆变器。该词起源于美国，现在通 用于世界各地。
To keep the thyristors and other electronic power systems cool, the interior of a modern locomotive is equipped with an air management system, electronically controlled to keep all systems operating at the correct temperature. The fans are powered by an auxiliary inverter producing 3-phase AC at about 400 V.
为了对半导体元件和其他电气系统进行冷却，现代机车内部都装有空气管理系统， 用电气控制来确保所有系统在正常温度下运行。由辅助逆变器为风扇提供400V的三相 交流电。
DC link is used on modem electronic power systems between the single phase rectifier and the 3-phase inverter. It is easy to convert the single phase AC from the overhead line to the 3-phase required for the motors by rectifying it to DC and then inverting the DC to 3-phase AC.
直流连接用于现代电气动力系统的单相整流器和三相逆变器之间。通过将接触网上 的单相交流电整流成直流电，然后再逆变成三相交流电，就很容易地将单相交流电转换 成牵引电机使用的三相交流电。
Inverter is a type of electronic power device mounted on trains to provide alternating current from direct current. It is popular nowadays for DC railways to allow three phase drive or for auxiliary supplies which need an AC supply.
Line breaker is a type of electro-mechanical switch in a traction motor power circuit used to activate or disable the circuit. It is normally closed to start the train and remains closed all the time while power is required. It is opened by a command from the driving controller, no-volts detected, overload detected and wheel spin or slide detected. It is linked to the overload and no-volt control circuits so that it actually functions as a protective circuit breaker.
线路断路器是用于接通或断开牵引电机供电线路的电子一机械开关。它在列车启动 时闭合，并在全部供电时间里持续闭合。在发现失压、过载或者轮对空转或滑行时，由 司控器命令将其断开。断路器连人过载和失压控制电路中作为保护电路。
Master controller is driver’s power control device located in the cab. The driver moves the handle of master controller to apply or reduce power of the locomotive or train.
Traction motors on electric locomotives get very hot and, to keep their temperature at a reasonable level for long periods of hard work, they are usually fitted with electric fans called motor blowers. On a modern locomotive, they are powered by an auxiliary 3-phase AC supply of around 400 V supplied by an auxiliary inverter.
为了使电力机车上的牵引电机在长时间的满负荷工作过程中，保持在适当的温度水平，它通常与叫做电机通风机的电动风扇配合使用。在现代机车上，由一台辅助逆变器 提供辅助三相400 V的交流电给牵引电机通风机供电。
Rectifier is a type of converter consisting of thyristors and diodes is used to convert AC to DC. A modern locomotive will usually have at least two rectifiers, one for the power circuits and one or more for the auxiliary circuits.
The air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes. The compressor is usually electrically driven and can therefore can be mounted anywhere.
Locomotives always carry sand to assist adhesion in bad rail conditions, sand is often provided on multiple unit train too.
Synchronous motor is a type of traction motor where the field coils are mounted on the drive shaft and the armature coils in the housing, which is inverse of normal practice. This is a single-phase machine controlled by simple inverter. Now it is superseded by the asynchronous motor.
牵引电机的磁场线圈安装在转子上，电枢绕组安装在定子（机壳、外壳）上，这 与正常情况正相反。它是一种由简单逆变器控制的单相机械，现在已经被异步电动机 取代。
Transformer is a set of windings with a magnetic core used to step down or step up a voltage from one level to another. The voltage differences are determined by the ratio between turn number of windings on the input side and the output side. An essential requirement for locomotives and trains using AC power is that line voltage has to be stepped down before being used on the train.
Current is collected from overhead lines by pantographs, as shown in Fig.2.3. Pantographs are easy in terms of isolation—you just lower the pan to disconnect the power supply to the vehicle. However, it is complicated to operate.
Since the pantograph is usually the single point power contact for the locomotive or power car, it must maintain good contact under all running conditions. The higher the speed, the more difficult the maintenance of good contact. We have already noticed the problem (above) of wave formed on the wire caused by a pantograph moving at high speed.
由于电力机车或者动车组的受电弓通常是点接触，所以必须在任何运行条件下保持 良好的接触。速度越高，保持良好的接触越困难。我们已经注意到由于受电弓高速移动 而产生接触网波动的问题了。
Pantograph contact is maintained either by spring or air pressure, compressed air pressure is preferred for high speed operation. The pantograph is connected to a piston in a cylinder and air pressure in the cylinder maintains the pantograph in the raised condition.