CC22 locomotive is a locomotive operated by PT. Kereta Api (Persero), in Regional Division III South Sumatra. This CC 202 type locomotive is in principle a Diesel Electric Locomotive.
Diesel Engine as a power source converts heat energy into rotary mechanical energy, which rotates a 3-phase AC electric generator that functions to convert rotary mechanical energy into electrical energy. The electric current that has been generated by the Generator through service tools and control systems is channeled to the Traction Motor to be converted into rotary mechanical energy to rotate the locomotive's drive wheels on the rails.
DE (Diesel Electric) locomotives are made by General Electric (CC201 and CC 203 series locomotives) and by General Motors (CC202 series locomotives). With advances in electronics, both locomotive manufacturers have developed electrical systems in power generation systems with AC (alternating) Alternator voltage which was previously with DC (flat) Generators and made changes to the service system by using semi-conductor devices in the form of Transistors, ICs, Capacitors, Resistors, SCRs, Diodes, and others, which are assembled in one Module according to their respective functions.
Understanding Silicon Controller Rectifier
Excitation in the Main Generator magnetic field comes from the Generator D14 exciter, 3-phase alternating current through the SCR assembly. Each SCR is connected in series with each phase of the alternating current exciter output in such a way that it can only flow when the phase has a positive voltage value (normal forward). This SCR has not flowed electric current even though at that time the phase has a positive value before the SCR gate is fired by the trigger signal from the SE Module.
After the trigger signal is given to its gate, the SCR becomes ON and current flows from the anode to the cathode. The flow of electric current will continue even though the trigger signal is disconnected. This flow occurs only during the positive period of the sine voltage graph. The SCR will automatically become OFF at the end of the positive period or the voltage becomes 0 Volts.
Figure 8.18. SCR Assembly Circuit - Japan Manual Instruction Railway, 1978
The ignition signal given to the SCR comes from the SE Module according to its needs to determine the amount of current flowing to the Main Generator field. The desired excitation amount is determined by comparing the signal from the load regulator to the signal from the FP Module in the form of a feedback signal. If the signal from the load regulator is momentarily greater than the FP Module, the Transistor on the FP Module works (ON) causing current to flow to the magnetic coil of the amplifier on the SE Module.
If the signal from the FP Module is momentarily greater than the signal from the load regulator, the Transistor on the FP Module does not work (OFF) resulting in no current flowing to the amplifier magnetic coil.
With the flow of current in the magnetic coil of the amplifier, the core will become saturated. This event causes the Transistor in the SE Module to work and then as a trigger signal on the SCR.
The saturation level in the coil core is determined by the current flowing in the control coil. The magnitude of this current is limited by the signal from the load regulator. If the magnitude of the signal from the load regulator is small, then the amount of current flowing to the control coil will also be small.
This causes the saturation level in the amplifier's magnetic coil core to run slowly at the time of the positive half-wave of the sine wave graph. Thus, the ignition signal will also be slow to occur at the positive half-wave, resulting in the ignition process only taking place for a short time during the positive period of the half-wave sine wave graph. Incidents like this cause the current flowing in the SCR to only be brief so that the excitation only lasts a short time between the positive periods of the sine wave graph.
If the signal from the load regulator is large, then the amount of current flowing to the control coil will also be large. This causes the saturation level in the core of the amplifier magnetic coil to occur quickly during the positive half-wave period of the sine wave graph. Thus, ignition will occur earlier during the positive half-wave. This incident causes the ignition process to take a long time during the positive half-wave period of the sine wave graph. So that the excitation will last longer as a result the current in the Main Generator will be greater and the locomotive power will also be greater.
This is how the SCR works, which is controlled by the signal that works on the transistor to determine the size of the excitation which ultimately regulates the locomotive power.
From the description above, it can be concluded that locomotive power control is controlled by signals originating from the operation of a system of active semiconductor devices in the form of transistors.
Load regulator
This load regulator consists of a resistor with a value of 1500 Ohm. Rheostat movement with a hydraulic system that uses oil pressure outside the diesel motor.
This load regulator forwards the signal from the RCe Module in the form of voltage and is passed through the WS Module to be distributed to the FP Module. The input signal in the form of voltage given to the load regulator depends on the position of the throttle handle and the condition of the capacitor on the RCe Module is in the charging position or has been fully charged.
At the throttle handle position 8, and the capacitor or condenser on the RCe Module has been fully charged, insert it into the load regulator by 50 volts. This voltage will decrease in proportion to the decrease in the throttle handle position. The voltage output by the load regulator depends on the amount of incoming voltage and the position of the wiper load regulator.
At the position of the load regulator is more or less the same as the incoming voltage. When the locomotive is running with a certain throttle handle position, the output voltage from the load regulator is determined by the input voltage and the magnitude of the Main Generator current. The function of the load regulator is not completely described in this description because to explain it must reveal how the diesel motor governor works with changing loading due to changes in the locomotive load.
Figure 8.17: Load Regulator
In the description here, only the function of the load generator is emphasized in its role of transmitting signals to control power electrically.
Understanding Feedback Signals
1. Generator Voltage Feedback Signal
To obtain this signal, a transformer obtains a channel from the GPTI Main Generator. With a smoothing circuit consisting of 6 (six) signal diodes from the transformer in the form of a voltage signal, it is passed through a series-connected resistance circuit in such a way that the voltage signal is
.525 volts is taken as 50 volts as a signal representing the 1525 volt signal. This signal is then used as a voltage control signal that comes out of the Main Generator.
2. Current Generator Feedback Signal
To obtain this signal a transformer takes the current out of the Main Generator. The magnitude of the current signal that comes out of the Main Generator through 6 (six) Diodes, the signal from the transformer is actually a voltage. By going through a series of Resistors, the current of 3,550 amperes from the Main Generator is represented by a voltage value of 50 Volts.
Furthermore, the current signal represented by a voltage of 50 volts is used to control the current coming out of the Generator via the FP Module.
3. Generator Power Feedback Signal
To control the power output of the Main Generator, the voltage feedback signal and the current feedback signal are combined in such a way that the combination of the two signals is compared with the signal from the Load regulator.
Comparison of signals from the Generator load with the Transistor series on the FP Module. Transistor biasing on the FP Module occurs when the signal magnitude from the load regulator suddenly increases greater than the magnitude of the power controller feedback signal.
In this position, the signal magnitude from the load regulator at a maximum price of 50 Volts. A signal of less than 50 Volts will occur if the locomotive experiences a change in load on an incline, but the power output from the Generator remains at 20,000 HP.
This happens because the GV Module works to maintain the output voltage from the Main Generator at 1,250 Volts. In addition, this voltage is also maintained by the operation of the FP Module which works to compare the signal and then regulates the excitation to keep comparing the Generator power at a constant price.
This is how the FP Module works in harmony with the Transistor which can regulate locomotive power of 2000 PK.
Module Voltage Regulation
To regulate the voltage output at a safe price, a compact circuit in the form of Modules is required for excitation and voltage regulation. These Modules will be explained briefly below.
1. GV Module -- Generator Module Settings
The GV module limits the voltage output to the maximum safe limit on the Main Generator. This setting is done by modulating the control signal to the SE Module when the voltage coming out of the Main Generator tends to increase. With the control signal increasing due to the increase in the voltage coming out of the Main Generator, it will result in a decrease in the excitation of the Main Generator's magnetic field.
Voltage regulation by GV Module is with a Transistor controlled by the increase in amplitude of pulses obtained from the tendency of voltage increase. Thus, the Transistor works by using pulses as feedback to regulate excitation to voltage.
Figure 8.9. Generator Voltage Regulation GV Module
2. GX Module (Generator Excitation Regulating Module)
GX Module to limit the excitation of the Main Generator when the current flowing into the Generator's magnetic field increases beyond the safe limit. The way this system works is by using a signal from a transducer whose signal size is proportional to the electric current flowing into the Main Generator's magnetic field. This signal is then modulated into the SE Module when the current increases beyond the safe limit.
The GX module consists of two transformers to modulate both signals from the magnitude of the current flowing from the exciter to the generator's magnetic field and the other from the magnitude of the output voltage from the exciter.
These two signals then act as controllers for the operation of the Transistor on the GX Module and then connect with the GV Module to jointly regulate the Main Generator excitation system.
Figure 8.10. GX Module Series
3. RC Module (Rate Control Module)
The excitation system in the Main Generator has a very fast response when the throttle handle is raised to a higher position. This causes the locomotive power to increase very quickly. Because this is not desired, it is necessary to have a control to regulate the increase in locomotive power smoothly and without surprises. For this purpose, a Resistor-capacitor timing circuit is used.
The basis of how this tool works is by using the capacitor charging time with a series of resistors. In this way, the transistor on the RCe module can be adjusted so that the excitation circuit can be timed.
Figure 8.11. RC Module Circuit
4. SE Module (Sensor Module)
The Sensor Module controls the amount of electric current for excitation in the Main Generator magnetic field. This current comes from the exciter through the SCR assembly which is assembled in a 3-phase bridge system. This SCR is not ON until the values on the anode are more positive to the cathode and also if the ignition signal has not been given to the SCR gate, then the SCR is ON, once the ignition signal is cut, the SCR remains ON as long as the anode is positive to the cathode.
The SE module functions to provide a signal to each gate on the SCR so that the SCR is ON, which allows electric current from the exciter to flow to the magnetic field of the Main Generator.
The electric current flowing from the exciter is alternating current, because the SCR circuit is a 3-phase bridge circuit, then the current can flow into the magnetic field only when the sinusoidal voltage is positive. The maximum current that can flow occurs at half the wave in the positive region. When the voltage value starts to become positive from the negative path and when the voltage will be 0 going to the negative region, that is the maximum amount of current that can flow into the magnetic field from each phase.
If the SCR ignition starts when the voltage starts to become positive, then the SCR will work during the full positive period, meaning the current flows at its maximum and results in maximum excitation as well.
On the other hand, if the SCR ignition occurs when the positive value approaches 0, then the SCR works only during the ignition time until the positive value will change to negative. Thus the main function of the SE Module is to regulate the SCR ignition time to obtain the amount of current for excitation that is in accordance with the needs.
5. TH Module (Throtle Response Circuit Module)
The TH module functions to create a stable voltage of 68 Volts for the purposes of the excitation control system, namely the voltage flowing to the CV Module, FP Module. This voltage is very stable which is obtained by using a Voltage Regulator circuit in the TH Module, which consists of an IC and several Transistors. The stability of this voltage is very necessary because it is used as a standard comparison quantity for the purposes of excitation control in the Main Generator field.
Figure 8.12. Sensor Module Circuit
Another function is to generate a signal proportional to the position of the throttle handle. The higher the throttle position the greater the signal given and vice versa. This signal is then as a voltage that is compared to the output voltage of the SE Module in the FP Module which regulates the work of the Transistor for the purposes of Main Generator excitation.
Another series of TH Module outputs will output voltage to operate the solenoid on the diesel engine governor. This solenoid operation will produce a signal that is used to control the rotation of the diesel engine.
This signal works logically and digitally. This signal is generated by a number of components, such as several opto isolator transistors on the TH Module. The TH Module circuit is very compact and complicated because it consists of several ICs, opto isolator transistors, diodes, and so on.
Figure 8.13. TH Module Series
6. EL Module (Excitation Limiting and Safety System)
This excitation safety system consists of an EL Module and a transducer that provides a signal to the EL Module proportional to the current flowing to the Main Generator field.
The EL module functions to prevent excessive excitation current in the Main Generator by regulating the operation of the EQP excitation relay circuit if the excitation current passing through the GX Module exceeds a safe value.
This transducer receives an AC signal from an exciter connected in series with the EL Module. The signal is generated from the induction in a coil whose core is induced by the electric current flowing for excitation purposes.
Figure 8.14. Excitation Limiter and Protection Circuit
If there is an excitation current that is more than a safe price, then a signal will be generated that is proportional to the increase in excitation current. This will cause the EL Module circuit on the Transistor to work and then break the circuit in the excitation system. At the same time, it will turn on the indicator light that indicates the occurrence of excess excitation current.
7. FP Module (Feedback Module)
The FP module functions to control the power coming out of the Main Generator at a price that is proportional to the position of the throttle handle. The working principle is with a signal system from the magnitude coming out of the Main Generator as a feedback signal which will then regulate the magnitudes so that the desired price is achieved. The feedback signal in the FP module is compared with the signal from the TH module.
Furthermore, the results of this comparison are used to control the SE module, namely the current flowing in the magnetic amplifier.
This control uses the voltage signal level and the current level of the Main Generator as a feedback signal. The combination of these two signals is then used as a signal that functions to control the power of the Main Generator.
Figure 8.15. Throttle Handle
Figure 8.16. Feedback Module Circuit
Working Principle of Diesel Electric Locomotive
To generate voltage and electric current in a 3-phase alternating current generator, a series of several devices working together and control of the module related to generating voltage and electric current are needed. The series is a current generating coil, a magnetic field coil, and a control system to obtain the voltage and electric current values according to needs.
Compared to previous locomotives made by General Motor, the CC 202 locomotive is very different. The difference lies in its excitation system which uses an exciter as a magnetic field generator in its Main Generator and a control system that uses active electronic components. Physically, this exciter is constructed together in one Main Generator shaft, but is electrically separated from each other. The generator and exciter are a 3-phase alternating current power generator with a rotating magnetic field system or in general terms rotating field, meaning the armature as the magnetic field generator, while the stator as the coil that generates electric current and voltage.
To flow electric current used as a magnetic field generator through a pair of slip rings. On the Generator shaft there are two pairs of slip rings, one to flow current to the exciter coil and the other pair to flow current to the Main Generator coil.
Figure 8.6. Main Generator
The current generation stage in the Generator starts from the Aux Generator which generates alternating voltage, this electric current is then leveled by the Diode which is arranged with a 3 phase bridge system and flows directly into the exciter magnetic field.
The voltage used here does not go through a voltage regulator, so the voltage that comes out on the aux generator will increase according to the rotation of the diesel engine. Likewise, the voltage generated on the exciter will increase according to the rotation of the diesel engine.
Figure 8.7. Exciter Generator
With the flow of electric current in the exciter magnetic field coil, a 3-phase alternating voltage will arise in the exciter which is generated in the stator coil.
This electric voltage will immediately arise as soon as the diesel engine is running, but has not yet flowed to the Main Generator magnetic field coil. The alternating current generated by the exciter, in addition to being a ready current for excitation purposes on the Main Generator, is also directly used to rotate the radiator cooling fan electric motor that uses a 3-phase alternating current electric motor. In addition, it is also used to rotate the diesel engine filter blower fan also using a 3-phase alternating current electric motor.
When used for Main Generator excitation purposes, its use is regulated according to requirements, according to the amount of power required.
The alternating current from the exciter which will be used to generate voltage in the Main Generator is flowed through a series of SCR (silicon control rectifier).
Before the SCR is turned on (ON), the electric current that will go to the Main Generator magnetic field coil has not flowed, meaning that the Main Generator has not generated an electric voltage. This condition will continue as long as the locomotive has not been powered.
When the locomotive is to be moved, the throttle is placed in position No. 1, then the TH Module will provide a signal with an electric voltage of 10.9 Volts, then it is distributed to the RC Module, then this voltage will come out at 8.45 Volts and continue to flow to the LR assembly and out to the Transistor base on the FP Module. The stable voltage from the THe Module of 68 Volts is distributed to the Transistor Emitter on the FP Module which is previously in series with the GV Module and the magnetic amplifier saturation winding on the SE Module.
With the presence of forward bias on the FP Module Transistor, because the Transistor is NPN type, this Transistor will be on (working) and current flows in its collector, so that a momentary signal will be generated in the SE Module as a result of the signal, the transformer in the SE Module will be induced. This induction is in the form of pulses which will then ignite the SCR so that the SCR is on.
With ON SCR then the alternating current in the exciter will flow to the Main Generator coil and a magnetic field will arise in the coil so that the Main Generator flows alternating electric current. The generation of pulses by the SE Module consists of three magnetic amplifier coils which will then ignite 3 SCRs alternately, so that the magnitude of the magnetic field in the Main Generator will be in line with the pulses generated by the SE Module.
The alternating current of the Main Generator is then channeled to the Traction Motor through Diodes to be converted into a flat current. The size of the Generator power will then be controlled by the length of the ignition on the SCR.
Figure 8.8. Wiring of CC202 Power System
CC202 Locomotive Electronic Module
This CC 202 locomotive has a slightly different way of service to obtain locomotive power. In the DE locomotive series CC201 and CC203 using electrical mechanics, but in the CC 202 locomotive using semi-conductors in the form of ICs, Transistors, Diodes, pulse signals, inductions that are connected in a circuit called a Module.
These modules are to control the system to obtain the required power with the needs. The number of modules in one locomotive is 13, each of which has a different function. From the entire electronic control system is divided into the following groups:
1. Generator and Voltage Control
This group includes:
- Main Generator and short circuit protection
- Auxiliary Generator
- Exit alternator
- Voltage controller (VR)
2. Excitation and Power Control System
- Exitation Module and feedback protection (EL Module)
- Feedback Module (FP Module)
- Generator Voltage Regulator Module (GV Module)
- Generator Exitation Regulator Module (GX Module)
- Load Regulator Assembly (LR)
- Rate Control Module (RC Module)
- Sensor Module (SE Module)
- Throtle Response and Volt Reference Module (TH Module)
- Silicon Rectifier Assembly (SCR)
- Load Regulator Assembly (LR)
- Rate Control Module (RC Module)
- Sensor Module (SE Module)
- Throtle Response and Volt Reference Module (TH Module)
- Silicon Rectifier Assembly (SCR)
3. Slip Detection and Safety System
- Wheel Slip Module (WS Module)
- Wheel Slip Bridge Circuit (WSBC)
- Wheel Slip Transductor (WST)
4. Dynamic Braking, Excitation and Control
- Dynamic Protection Module (DPe Module)
- Dynamic Brake Regulator Module (DR Module)
5. Indicator Lights and Auxiliary Tools
- Annunciator Module (AN Module)
- Sanding Module (SA Module)
The 13 modules are assembled and each consists of a Transistor, IC, SCR, Diode, Capacitor, Resistor, Transformer, Transducer, Opto Transistor, each of which has a different function.
Maintenance of Industrial Equipment Wiring Systems
Electrical wiring in industry contributes as a medium to channel electrical resources to electrical equipment, such as electrical machines, controls, and other electrical devices. This chapter will explain the grouping of wiring in industry. It will also explain real case examples related to wiring problems and maintenance of devices related to wiring problems, namely the case of train locomotives. For other wiring problems, you can read other sources, such as PUIL, IEC, and others.
Wiring Grouping
In principle, the electrical wiring circuit is divided into four parts, namely the power source, transmission line, control device and devices that use electrical power.
1. Resources
The power supply source usually consists of a distribution panel for 220 V/340 V, the total ampere capacity of which is generally 60 -- 200 A. Each circuit in the panel box is connected to the neutral-ground line and the phase line.
Inside the panel there is a power lag, which is a black or red wire if 220 V voltage is used. The neutral-ground path is usually a white wire, and green which functions as a grounding safety for household equipment or other equipment. The neutral-ground path is always connected to the ground, or the street ground or cold water pipe depending on local code.
2). Transmission Line
In an industrial location, or in a city, you can often find poles with several wires stretching from one pole to another. This is a path for distributing electrical power sources. Distribution lines can be made above ground, as shown in Figure 8.2, or buried in the ground. On the pole there are several important components, such as fire or lightning protection devices, insulators, boxes for regulating power lines, anchors and several clamps or clamps, as shown in Figure 8.2.
3). Control Equipment
In industry and at home, many control devices are found, such as switches to turn on or off lights, machines, or other devices, either manually or programmably, so that many human jobs can be replaced by control devices. Currently, many control devices are used for household appliances, such as washing machines. Figure 8.3 shows one of the programmable control devices.
4). Equipment that uses electrical power
Most of the devices in the industry work using electrical power sources, both AC and DC, starting from lighting systems, control systems, information systems, measuring and entertainment equipment, and so on. The maintenance of these equipment has mostly been explained in the previous chapter and or after this chapter.