Exercise questions for EMU mechanics and technicians

Theoretical test scope of EMU mechanic induction examination

4. Short answer questions

1. What are the main identification marks that EMUs should have?

Answer: Road emblem, abbreviation of the assigned section, vehicle model, vehicle number, capacity, dead weight, load, overall length, maximum operating speed, manufacturer name and date, date and location of scheduled maintenance, should be "No Climbing Due to High Voltage Danger" sign.

2． Briefly describe the responsibilities of EMU on-board mechanics.

Answer: ⑴ Conscientiously implement rules and regulations, obey orders and instructions, and earnestly perform prescribed duties.

⑵ Responsible for monitoring the technical status of the EMU during operation, notifying the driver of relevant information in a timely manner if a fault is discovered, and taking measures to properly handle it.

⑶When the EMU enters and exits the station, it is responsible for handling technical handover with the EMU.

⑷Under the command of the driver, handle work related to driving, train protection and accident rescue.

⑸When a breakdown or other emergency situation that endangers driving safety occurs, promptly notify the driver to take parking measures or use the emergency brake valve to stop.

⑹According to the driver’s notification, responsible for opening and closing the doors of the CRH2 EMU.

3． Briefly describe how the EMU numbering rules are stipulated?

Answer: The model and car number of the EMU are as follows:

The technical serial code distribution of the model and car number of each type of EMU is as follows:

BSP EMU Group - 1

Sifang Co., Ltd. EMU - 2

Tangshan Co., Ltd. EMU - 3

Changke Co., Ltd. EMU - 5

The manufacturing serial codes of various EMU models and train numbers: EMUs with different technical sequences are arranged separately, in sequence from 001 to 999.

The model series codes of various EMU models and vehicle numbers: Different model series codes are determined according to the speed level and vehicle type of the EMU.

4. Briefly describe the regulations of the Ministry of Railways on monthly EMU wheel set inspection and measurement.

Answer: Conduct a registered manual inspection and measurement of EMU wheel pairs once a month, focusing on checking the technical conditions of rims, treads, rims, brake discs and brake pads, and measuring rim thickness, Tread circumferential wear size and brake disc and brake pad thickness, etc.

5． Briefly describe the main responsibilities of a ground handling mechanic.

Answer: ⑴ Responsible for the use and management of EMU equipment.

⑵ Responsible for cooperating with vehicle shunting, passenger transportation preparation, cleaning, sewage suction operations, and checking the quality of sewage suction operations.

⑶ Responsible for the anti-freezing of the EMU.

⑷ Responsible for handover with on-board mechanics.

6． Briefly describe how the maintenance cycles of CRH1, CRH2 and CRH5 EMUs are regulated.

Answer: The EMU maintenance cycle is divided into one and two levels. The first-level maintenance is performed after each operation or within 48 hours (the cumulative operation of CRH1 and CRH2 does not exceed 4,000 kilometers, and the cumulative operation of CRH5 does not exceed 5,000 kilometers). Secondary maintenance is divided according to each type of EMU. CRH1 type is carried out every 15 days, CRH2 type is carried out every 30,000 kilometers or every month, and CRH5 type is carried out every 60,000 kilometers.

The regular maintenance cycles of EMUs are divided into three, four and five levels. According to various types of EMUs, the maintenance cycles of CRH1 and CRH5 are the same, with level three maintenance of 1.2 million kilometers, level four maintenance of 2.4 million kilometers, level five maintenance of 4.8 million kilometers, CRH2 type three maintenance of 450,000 kilometers, and level four maintenance of 90 10,000 kilometers, and 1.8 million kilometers of five-level maintenance.

7. What measures should generally be taken when maintaining electronic equipment on EMUs or working near them?

Answer: When performing maintenance on or working near electronic equipment, you must always use special protection for sensitive parts and ground your body with an electrostatic wrist strap to prevent static electricity from damaging circuit boards, computers and controls. units and other electronic equipment.

8． What are the regulations on the trial operation of EMUs?

Answer: A trial run must be arranged before a newly built EMU or EMU is put into operation after Level 4 or 5 maintenance. In principle, the trial run distance should be no less than 500km; the trial run speed of a 200km/h EMU is 160~200km/h. h, the trial operation speed of the 300km/h EMU is 250~300km/h.

4. Briefly describe the number of temperature sensors in the driver's cab air conditioning system and their installation locations?

Answer: The EMU driver's cab air conditioning system is equipped with three temperature sensors, which are located on the roof. A return air temperature sensor and a supply air temperature sensor in the air conditioning unit unit, as well as a room temperature sensor in the cab.

5. Briefly describe the number of temperature sensors in the passenger cabin air conditioning system and their installation locations?

Answer: The EMU passenger cabin air conditioning system is equipped with 10 temperature sensors, including 1 fresh air temperature sensor. , 1 return air temperature sensor and 2 supply air temperature sensors are located in the roof air handling unit (AHU), and the other 6 room temperature sensors are distributed in the passenger compartment.

6. What working modes can the passenger room air conditioning control system set the air conditioning unit to in normal mode?

Answer: In the normal mode, the passenger room air conditioning control system can set the air conditioning unit in the following modes according to the cooling and heating requirements: ventilation mode, pre-cooling mode, cooling mode, preheating mode and heating mode.

7. Briefly describe the working principle of the EMU holding brake

Answer: As long as the EMU is in the stopped and raised state, the holding brake will be automatically implemented. It can be used to prevent trains from rolling when parking and prevent trains from rolling when driving and parking on a 30‰ slope. Holding the brake can be temporarily inhibited by a button on the driver's console.

8. How to manually open the upper pedal for maintenance?

Answer: 1. Close the air supply plug door of the upper pedal;

2. Pull the upper pedal forward and upward to the fixed position;

3. After pulling it out into place, insert the safety latch to prevent the pedal from being retracted accidentally.

9. What are the working modes of the mode selection switch in the guest room air conditioning control cabinet?

Answer: The mode selection switch in the passenger room air conditioning control cabinet is equipped with automatic position, manual position, closed position and test position.

10.

21. Briefly describe the working principle of traction converter.

Answer: The working principle of the traction converter is to rectify the input voltage of the traction transformer into DC1650V and then invert it into the three-phase AC drive voltage required by the traction motor, and at the same time convert the output from the DC1650V DC link. AC876V is sent to the three-phase transformer of the filter box, and finally the three-phase transformer outputs AC400V to the auxiliary electrical equipment of the entire vehicle. In addition, during the regenerative braking process, it is responsible for feeding back the electric energy generated by the traction motor to the power grid.

28. Please write down the braking type of CRH1 EMU?

Answer: Normal braking, regenerative braking, maintaining braking, emergency braking, parking braking, and anti-icing braking.

29. What is the main function of the traction control unit PCU?

Answer: The main function of the traction control unit PCU is to control the work of the entire converter system through DCU/L, DCU/M and DCU/A, so that the main traction system completes the AC-DC operation of the system. -AC conversion process, finally drives the motor for traction and makes the auxiliary power supply system output three-phase AC 400V.

30. What are the functions of each position of the automatic speed control selector switch?

Answer: 1. The left digit indicates the selection of the connected speed state;

2. The middle digit indicates the selection of the normal speed state controlled by the main controller;

3. The right digit indicates the selected cleaning speed state.

32. What does it mean when the "Class A fault" indicator light is off or when the red light is on during the operation of the EMU?

Answer: 1. When it is not lit, it means that there is no Class A fault in the train set;

2. When the red light is on, it means that there is a Class A fault in the train set.

33. Please write down the meaning of the abbreviations of the following equipment installation directions?

Answer: U--underframe area/bottom area; R--roof; P--passenger room area; H--the partition between the roof and the passenger room; C--driver's cab

35. Briefly describe the working conditions of the EMU HVAC air-conditioning system in tunnel mode?

Answer: When the EMU HVAC air-conditioning system is in fire mode, the operating conditions of the unit are as follows: 1. The fresh air damper is closed; 2. The waste exhaust air door is closed; 3. The return air damper is fully opened; 4. , the waste exhaust fan stops working.

36. Briefly describe how many batteries the EMU is equipped with? Name its main function?

Answer: The EMU is equipped with five batteries. Its main function is to supply power to the EMU's control system, lighting, emergency lighting, emergency ventilation unit, radio system and other equipment.

37. What are the main control safety circuits of CRH1 EMU?

Answer: It is mainly divided into traction safety circuit and emergency braking safety circuit.

38. What are the main components of the EMU fire alarm?

Answer: It is mainly composed of a smoke alarm host, a controller panel and various types of sensors.

39. What are the main components of the primary suspension device of the bogie?

Answer: 1. Axle box spring; 2. Axle box vertical hydraulic shock absorber; 3. Positioning arm device.

40. Which traction subsystems are included in the traction control system connection?

Answer: Including: 1. Grid-side converter control system; 2. Motor converter control system; 3. Auxiliary converter control system; 4. Battery charger control system

1. How to adjust the seat direction in the guest room?

Answer: There is a foot switch on the lower side of the seat. When it is necessary to rotate, press the switch with your foot and push the seat with your hand to rotate the direction. Thereby adjusting the seating direction of the seat.

2. What is the operating temperature of the shaft temperature detection device?

Answer: When the bearing temperature reaches a certain value, the thermal fuse will melt and issue a notification of abnormal shaft temperature. The specifications of the device are as follows:

Operating temperature: 165℃＋0℃～-10℃ (temperature slope 5℃/min)

Set temperature of built-in thermal fuse: 144 ℃

3. How to install the fire extinguisher in the CRH2 car?

Answer: Fire extinguisher settings:

⑴Car No. 1 and No. 8: 2 cabs and 2 pass-through stations.

⑵ Cars No. 2, 3, 4, 5, and 6: 2 one-passenger stations and 2 second-passenger stations.

⑶Car No. 7: 3 corridors and 2 crew cabins.

4. What operating modes does the air conditioner have?

Answer: ventilation; cooling; heating; forced cooling; forced heating

5. How to set the temperature inside the car?

Answer: Enter the set temperature by touching the up and down keys on the air conditioner setter.

Rising: Each time the key is pressed, the temperature rises by 0.5℃ (the maximum rise is to 40.0℃).

Down: Each time the key is pressed, the temperature drops by 0.5℃ (the maximum temperature rises to 10.0℃). until)

Touch the setting button to complete the setting.

6. Briefly describe the function of the outer windshield.

Answer: The outer windshield is used to suppress the noise from the side of the car body, and to prevent passengers from falling and suppress the vibration of the car body when parking. A compressed outer windshield is used to make the space between the car body The vehicle joints are smooth.

7. What are the safety equipment in the CRH2 car?

Answer: There are emergency ladders, transition boards, fire extinguishers, fire alarm buttons, emergency alarm buttons, bathroom emergency buttons, etc.

8. What are the main components of the EMU UHV electrical system?

Answer: The EMU UHV electrical system includes major components: pantograph, protective ground switch EGS, fault isolation switch, vacuum circuit breaker VCB, lightning arrester, high-voltage cable and high-voltage connector.

9. What information can the train control vehicle-mounted equipment obtain from the ground information obtained from the ground transponder through the transponder information receiving antenna and the transponder information receiving unit (BTM)?

Answer: Obtain the line information ahead; determine the location of the train; determine the running direction of the train; obtain route information; obtain temporary speed limit information.

10. Please tell me the steps to remove the brake pad?

Answer: ⑴ Cut off the anti-loosening wire of the lower bolt; ⑵ Loosen the bolt, remove the bolt and flat washer (be careful to prevent the brake pad from falling); ⑶ Use a spring pin to hold the brake pad base opposite to the axle Rotate one side and pull out the brake blade (when the brake blade is fixed and difficult to pull out, use the pull-out hole of the brake blade to pull it out).

11. Please tell me how to repair the toilet flushing device?

Answer: ⑴ Remove the toilet auxiliary nozzle (3 places) and clean the nozzle part.

⑵ Blow and clean the main nozzle (1 location) of the toilet.

⑶ If the flushing water flows out abnormally, replace the main nozzle or auxiliary nozzle with a new one.

⑷Put urine scale remover into the toilet to clean the flow pipe.

12. Please tell me how to repair the urinal flushing device?

Answer: ⑴Open the inspection cover on the upper part of the urinal and replenish the treatment agent into the treatment agent cylinder. When replenishing the treatment agent, it should be done under the condition of sensing by the photoelectric sensor. (2) Remove the mounting screws of the urinal cover, remove the cover, and check that the appearance of the pipe system is free of corrosion and leakage. ⑶ Use urinary stone remover to clean the urinal deodorizing valve and the inner wall of the sewage pipe leading from the toilet.

13. Please tell me how to repair the waste tank device?

Answer: ⑴ Check the appearance of the cabinet for no deformation or cracks. ⑵ Check that the sewage suction port and sewage suction valve should be free of deformation, cracks, and damage. ⑶ Check that the intake valve appears to be in good condition and that the intake valve plug moves flexibly. ⑷Open the dirt box switchboard and check the appearance. There is no abnormality in the electrical appliances and wiring.

14. Please tell me what are the service equipment control functions of the CRH2 EMU on-board information system?

Answer: ⑴Control the display content of the in-car information display and destination display; ⑵Control the display content of the car number display; ⑶Transmit broadcast time information to the automatic broadcast device; ⑷Transmit kilometer mileage to the broadcast service device Information; ⑸ Turn off the broadcast output of other groups when demarshalling; ⑹ Control and status display of service equipment (air conditioners, indoor lights, broadcasts).

15. Please tell me what the data recording function of the CRH2 EMU on-board information system includes?

Answer: ⑴ Record equipment action information when a fault occurs; ⑵ Record status when a main fault occurs; ⑶ Accumulated kilometers traveled and traction/regeneration power; ⑷ Record vehicle performance, project selection, and air conditioning during official operation or trial operation Operation rate, air conditioner operating status and other information.

16. Please tell me the operation process of antifreeze and drainage work for CRH2 EMU?

Answer: Pressurized retention function pipeline drainage (operating when power is available) → vehicle drainage (warm water tank, electric tea stove, water storage pipeline, wiper) → water pump drainage → various water equipment on the vehicle The action is drainage → water tank drainage → dirt tank evacuation → water seal drainage

17. Please tell me what are the main features of the CRH2 EMU bogie?

Answer: It adopts lightweight design, welded structure, second series air spring, disc brake, swing arm axle box positioning, single tie rod traction, motor suspension, etc.

18. The EMU displays the train logo at the head and tail respectively. The display method is the same during the day and at night. It does not need to be displayed during the day. Can you please explain how it is displayed?

Answer: The headlights of the driver's cab at the front of the EMU in the running direction display a white light forward, and the headlights of the driver's cab at the rear of the EMU in the running direction display a red light backwards. When the EMU is returning without power or being pushed, the driver's cab at the front end of the running direction displays a white light forward, and the driver's cab at the rear of the running direction displays a red light backwards. There is no need to hang side lights.

19. Briefly describe the status of each indicator light when the CRH2 side sliding door is opened and closed?

Answer: When the side sliding door is closed, the door closing indicator light on the driver's station will be on and the indicator light on the vehicle side will be off. However, when the side sliding door encounters an obstacle and the door cannot be closed or the door closing switch does not work properly, the vehicle side indicator light will be on. The indicator light is on, and the door closing indicator light on the driver's console is off.

20. Briefly describe the bicycle mitigation operation process?

Answer: Open the operating switchboard cabinet, open the angled plug door of the train tube, and then pull out the emergency button to short-circuit the braking circuit of the vehicle.

21. Briefly describe whether the air-conditioning equipment and lighting are powered off when the EMU crosses the phase zone, and explain the reasons?

Answer: When the EMU crosses the phase zone, the air conditioning device and lighting system are powered off; because the EMU control system sets a delay time of 20 seconds, during which the EMU passes through the In the Xiang area, the lights on the car will not be cut off and the air conditioning unit will stop working.

22. What is auxiliary braking?

Answer: It is set up for use when the brake control device is abnormal, the brake command line is disconnected, and during rescue, etc. Operate the setting switch on the driver's console and the switchboard switch of each unit (TC car) to operate. Different from normal and quick braking, the braking force is a fixed value independent of speed.

1. Briefly describe the functions and characteristics of the CRH1 EMU tunnel mode?

Answer: It is used to prevent bad external air from entering the carriage and affecting the air quality in the carriage when the EMU passes through the tunnel. At this time, the waste exhaust air door of the HVAC air-conditioning system is closed and the return air air door is opened.

2. Briefly describe the working conditions of the HVAC air-conditioning system of the CRH1 EMU in fire mode?

Answer: When the EMU HVAC air-conditioning system is in fire mode, the operating conditions of the unit are as follows:

1. Stop the cooling or heating function of the air-conditioning system;

2 , the fresh air damper and waste exhaust air door are in the fully open position, and the return air damper is in the normal position;

3. The two waste exhaust fans will use the maximum airflow to remove smoke from the car.

3. What are the levels of maintenance for CRH2 EMUs, and what is the maintenance cycle?

Answer: Maintenance is divided into five levels. Level one and level two maintenance are operational maintenance, and level three, level four and level five maintenance are periodic maintenance. The first-level maintenance cycle: 4,000 kilometers or 48 hours of operation; the second-level maintenance cycle: 30,000 kilometers or 30 days.

4. What are the protection and detection items for the fault protection function of the CRH2 EMU auxiliary power supply device?

Answer: Input overcurrent, converter overvoltage, converter overcurrent, converter overload, output overvoltage, output low voltage, ground detection, and output short circuit.

1. When the CRH1 EMU is in operation, how to deal with the failure of the main circuit breaker not opening according to the instructions?

Answer: 1. If the circuit breaker of the TP vehicle owner does not open according to the instruction, another pantograph should be installed according to the situation to ensure that the vehicle group has 60% power.

2 If the circuit breaker of the TB vehicle owner does not open according to the instruction, the two adjacent circuit breakers will also be blocked, and the vehicle group has 40% power. At this time, the Tb vehicle P1 should be moved at the appropriate time. Pick out the wire number (317201A) of pin 1 on the .K2.T.X21 terminal strip and wrap it up. Then, cut off the circuit breaker of the Tb car on the IDU (it must be cut off!), then lower the bow and reset it. At this point, the train will have 80% of its power available.

2. What high-voltage equipment is installed on the roof of CRH1 EMU Tp?

Answer: Mainly equipped with pantograph, main circuit breaker, line circuit breaker, voltage transformer, current transformer, surge arrester, RC filter unit and transient inductor.

3. Briefly describe what equipment is in the crew room of CRH2 EMU?

Answer: Generally speaking, there are in-car information displays, automatic playback devices and control amplifiers, 20W fluorescent lamps, monitoring speakers, plug-in connectors, vehicle information display control devices, emergency brake switches and crew side pulls. Door switches, fire extinguishers, emergency lights, emergency brake switches, etc. are also provided.

4. Please tell me what are the functions of cutting off and resetting the on-board information system equipment of CRH2 EMUs?

Answer: ⑴ Transmit reset command to traction converter, auxiliary power supply device and switchboard; ⑵ Transmission of remote equipment removal command; ⑶ Control of auxiliary winding power induction circuit; ⑷ Three-phase AC400V power induction circuit Control (BKK remote opening and closing operation).

5. Questions and Answers

1. What are the basic requirements and operating procedures for contact network interruption and power supply in the EMU?

Answer: 1. The EMU designates a dedicated person to be responsible for the operation and monitoring of catenary power outages (one person to operate and one person to monitor), the handling and confirmation of catenary power outages, the protection and confirmation of catenary power outages and grounding, and other related tasks. Personnel working on contact line power outages must be trained and certified to work.

2． In principle, applications for contact line power outages should be made in accordance with the shift operation plan time and procedures. Plan changes must be approved by dispatch.

Power outage:

⑴ Before the catenary power outage operation, the relevant maintenance personnel must apply to the dispatcher and go through the catenary power outage procedures.

⑵ The power outage operation can only be approved after dispatch confirms that the power outage conditions are met.

⑶ When the power is out, the power outage operator should wear protective gear and disconnect the isolation switch under the supervision of the supervisor. After disconnection, use the electric measuring pole to test the catenary. After confirming that there is no power, hang the ground pole to implement power-off and grounding protection of the catenary.

⑷Relevant work teams should be notified before and after power outage.

Power supply:

⑴ Before the catenary power supply operation, the relevant maintenance personnel must apply to the dispatcher and go through the catenary power supply procedures.

⑵ The power supply operation can only be approved after dispatch confirms that the power supply conditions are met.

⑶ During power supply operation, under the supervision of supervisors, the power outage operators are required to wear protection, remove the grounding protection of the contact network, and close the isolation switch.

⑷Relevant work teams should be notified before and after power supply.

5. The formalities for power outage from the contact line must be registered and signed.

6. There should be clear warning signs indicating whether the catenary is powered or not.

7. Check the contact line power supply and disconnection tools according to regulations.

2. Explain the requirements for the infrared axle temperature detection system to detect EMU axle temperature and predict hot axles.

Answer: ⑴The infrared system must detect the axle temperature of the EMU.

⑵ The axle temperature monitoring of EMUs is mainly based on on-board detection systems, supplemented by ground-based infrared system detection.

⑶ When the infrared system detects the hot axle alarm of the EMU, the infrared attendant will dispatch the alarm to the train according to the prescribed procedures, but will not stop the train. The train dispatcher must immediately notify the driver, and the driver immediately notifies the onboard mechanic. The onboard mechanic will determine whether the EMU continues to operate safely based on the detection situation of the on-board axle temperature detection system. The driver will report the handling situation to the train dispatcher, and the train dispatcher will feedback infrared light. Duty clerk.

⑷The hot axle prediction standards for EMUs in the infrared system shall be implemented in accordance with the hot axle prediction standards for passenger cars of each bureau.

3. Explain the safety regulations for CRH1, CRH2, and CRH5 EMUs under the condition of water accumulation on the line.

Answer: ⑴ When the line surface is 100 mm higher than the track surface, the CRH1 EMU is prohibited from raising the power supply. CRH1 EMUs parked on lines with stagnant water 150mm higher than the track surface must undergo strict inspection and appraisal and be reported to the ministry for approval before use.

⑵ When the line surface is 60 mm higher than the track surface, the CRH2 EMU is prohibited from raising the power supply. CRH2 EMUs parked on lines with stagnant water 90mm above the track surface must undergo strict inspection and appraisal and be reported to the Ministry for approval before use.

⑶ When the line surface is 100 mm higher than the track surface, the CRH5 EMU is prohibited from raising the power supply. CRH5 EMUs parked on lines with stagnant water 200mm above the track surface must undergo strict inspection and appraisal and be reported to the ministry for approval before use.

⑷ During operation, when the driver finds that the accumulated water on the line is higher than the track surface, he should immediately take measures to stop the train, report to the train dispatcher, and instruct the train staff to carry out inspection, protection and other related work.

5. Describe the fire prevention responsibilities of on-board mechanics of CRH series EMUs.

Answer: ⑴ Before leaving the warehouse, check and confirm the status of electrical and fire-fighting equipment according to operating standards, and complete joint inspection and handover.

⑵ During operation, inspect and inspect vehicle electrical equipment, automatic fire alarm controllers and other equipment as required, and handle hidden dangers and faults in a timely manner.

⑶ When a fire occurs, promptly notify the driver according to the fire accident emergency plan to take parking measures or use the emergency brake valve to stop the vehicle; do a good job in driving, train protection and accident rescue work under the driver's command, and be responsible for the CRH2 type EMU centralized control switch door operation.

(4) Operate EMU equipment according to regulations, guide passenger transport personnel to use equipment correctly, and stop and correct violations.

⑸ Carry out safety inspection and handover after the EMU arrives.

1. Write down the various operations of the key interlock system when unpacking and inspecting the converter, and write down the functions of each main grounding operation?

Answer: 1. Turn the interlock switches of Tp1, Tp2 and Tb cars to the OFF position and take out the blue key. The main function of this operation is to cut off the air supply of the pantograph so that the car crew cannot raise the pantograph. Receive flow.

2. Use three blue keys to operate the grounding interlocking mechanism on the main circuit breakers of Tp1, Tp2 and Tb cars, and take out three yellow keys. The main function of this operation is to reliably ground the main circuit breakers.

3. Use one of the yellow keys to ground the AC400V busbar on the Tb car, and then take out a black key. The purpose of this operation is to ensure that the AC400V busbar of the EMU's auxiliary power supply system is in a grounded state.

4. Insert the two yellow keys and one black key that were previously removed into the safety interlock key box on the Tb car, and take out one of the white keys.

5. Use the white key to set the grounding handle in the converter box to the grounding position, and finally take out the red key and open the converter box for inspection. The main function of this operation is to ground the DC link in the converter to ensure that the capacitors on the DC link are completely discharged.

6. Finally, use the taken out red key to directly open the converter box for inspection and maintenance.

2. What are the main conditions that can lead to emergency braking?

Answer: 1. Press the emergency braking button

2. The main control handle is placed in the emergency position

3. Emergency braking caused by DSD device

4. Emergency braking required by ATP

5. The total wind pressure is less than 600KPa during normal operation

6. The emergency safety circuit loses power

7. Emergency braking requested by the brake computer

8. Passenger emergency braking action

3. Write down the working principle of the pantograph lifting pantograph?

Answer: After the EMU presses the pantograph lifting button, the pantograph air supply solenoid valve is energized to supply air to the pantograph lifting circuit. After the ascending air path passes through the air filter to remove moisture and the ascending throttle valve limits the flow, it enters the precision pressure regulating valve to adjust the total air pressure to the normal ascending pressure of 3.2-3.8bar. The adjusted compressed air inflates the lifting air bag to drive the mechanical device to complete the lifting action of the pantograph. The action value of the safety valve is 4bar, which ensures that when the precision pressure regulating valve is damaged, the total air pressure will not directly enter the lifting airbag, causing damage to the airbag.

28. Briefly describe the startup process of the grid-side converter LCM in the traction converter

Answer: 1. The drive control unit DCU/L of the grid-side converter is started command, the charging contactor is closed to precharge the DC link capacitor through the charging resistor;

2. When the DC link capacitor is charged, close the line contactor.

3. The other line contactor is also closed, then the charging contactor is disconnected, the charging circuit is stopped, and the grid-side converter LCM completes the startup and outputs DC1650V.

29. Briefly describe the working principle of the automatic switch monitoring program of the rear view system of the CRH1 vehicle's driver's cab.

Answer: When the driver's cab is activated, the monitor will automatically start to communicate with the vehicle crew. There is an automatic opening/closing program associated with the running speed. The principle of the automatic opening/closing program is as follows:

1. When the vehicle group accelerates to the set value of 70km/h, the speed is transmitted from the TCMS through the digital input module The system is transmitted to the rear view system, and the monitor will automatically turn off at this time;

2. When the running speed of the vehicle group drops to 10km/h, the monitor will automatically turn on;

3. When the monitor automatically shuts down, the monitor can also manually press the standby button to stop the automatic switch program and directly start or close the monitor's display function manually.