Network Rail Assessment Centre Prep Flashcards
Describe yourself: (self-starter and curious to learn)
What is Ohms Law?
Current and voltage are directly proportional (linear graph) -> resistance is constant i.e resistor. An example of a non-ohmic component is a filament lamp evident from the I-V graph
What is renewable energy and some examples?
Energy derived from sources that meet contemporary needs without jeopardising energy access for future generations i.e solar, wind, hydro, geothermal. Finite energy sources/non-renewable energy sources include fossil fuels and nuclear.
Factors to consider when sizing cables
Be able to withstand a short circuit:
Depends on fault current amount, insulation of the cable, the time duration of the fault
Current carrying capacity:
Must be able to deliver the expected load current
Voltage drop across cable:
Cable has some resistances and reactances causing a voltage drop, should remain within an acceptable limit to ensure connected equipment function properly (i.e motor)
Insulation material:
Air cables require UV and mechanical protection, also protection against heat and moisture
Describe what three-phase is
The three phases are offset by 120 degrees so when the net signal is averaged out it is more constant/linear compared to a single sine wave.
Three phase power and resistance triangles (real, imaginary, complex)
P=(root3)IVcos(theta)
cos(theta)=power factors
theta=angle between voltage and current
More power for the same amount of wire
Constant torque (power output)
AC and DC transmission
DC:
-No need to frequency match when transmitting power between systems (no Hz in DC)
-Requires more infrastructure as power is generated and received in AC (DC converters required at both ends)
-Smaller cables required in DC as AC has skin effect (actual current only travels in a small ‘skin’ portion of the cable)
-No reactive power in DC so less losses
-AC->DC rectifier (full wave or half wave) diodes to control current flow in one direction (capacitor to smooth the signal)
-DC->AC inverter, uses a 4 switch switching controller to switch the current flow (PWM to make it sine wave like)
Where do you see yourself in 5 years?
I see myself progressing within the company to more managerial/senior roles where I will have more responsibility on projects and imparting my knowledge and expertise to train fresh engineers working at the company.
Gaining chartership and maybe pursuing my Masters degree alongside my standard work duties.
Describe the skills you learnt in your plumbing work experience
Learnt how waste management systems are designed in residential buildings and their requirements (p-traps)
Learnt how to solder copper piping to repair leaks (abrasive to sand down the connection, apply flux, heat the pipe, apply the solder around)
Location of stop valves
Different materials used in waste systems such as ABS and PVC and how to properly prime PVC to ensure the glue properly adheres.
Liaised with clients to make sure they understood the scope of the project (how long it would take)
What are some considerations in railway infrastructure
location: does it impact local natural environments negatively such as negatively impacting ecosystems
demand: is there a demand for faster public travel in this area where it’s presence will generate a return
size: if there is a demand how large is it? how big is the local population?
Climate journey: transmission line feed to the train must adjust and be able to tunnel through obstacles
How is power supplied to a train?
AC overhead transmission cables 25kV connected via pantograph (adjustable height, and zigzags to vary to connection point for heat dispersion)
Then goes to step down transformer to feed induction motors 2kV
Then goes to rectifier to turn AC into DC
Then goes to inverter to turns DC into three-phase AC (uniform torque output)
Tracks are a grounding point
Signalling and Sensor Networks
Signalling:
Used for track safety and flow of trains in operation, also for maintenance safety
Sensor Networks:
-Vision sensors (ultrasonic) for object location on a track and departures
-Sensors to detect the integrity of tunnels (landslides/rockfall)
What are the biggest threats to the company? Who are our competitors? Innovation at network rail
Europort, SNCF Group
What kind of activities you expect to do on a daily basis while working at Network Rail?
Begin with foundational business familiarisation, learning about each part of the railway system (electrification, signalling, telecoms)
Contribute to delivery of major projects across the railway (maintenance, testing, design, renewed)
Why this graduate scheme/role?
Having immediate impact on real world rail projects contributing the the companies drive towards Net Zero.
Scheme structure:
Develop my knowledge and experience across a range of disciplines such as Electrification, Telecomms and Signalling; and later honing in on a specific one to gain an even deeper understanding through formal placements.
Technical and soft skills modules trained at the company including safety, also leadership modules to help me transition to more senior roles later in my career at the company
Joining a network of graduates but also receive support from seniors + my mentor
Furthermore, the companies support for chartership is something I’m personally interested in as I would like to gain that internationally recognised qualification and imrpove my technical skills as an engineer while while working for the company
Why do you want to work at network rail? Sustainability and Safety
One reason why I want to work for network rail is because the comapnies focus on sustainibility, where the comapany pledges by 2050 to be carbon neutral by protecting and maintaining the natural environments around the railway. But also a stronger focus on wasting less and recycling more materials. This is important as the company will contribute less to global warming and be less destructive to important ecosystems around the country.
I personally am really interested in sustainbility which is evident from a project i did which was finding ways to improve solar cell efficiency by surface texturing where I modeled all the physics in COMSOl and designed the structures in Rhino CAD
Furthermore, the companies support for chartership is something I’m personally interested in as I would like to gain that internationally recognised qualification and imrpove my technical skills as an engineer while while working for the company
Another reason is the companies safety initiatives such as educating the local community about rail safety and also protecting your employees through things such as safer trackside working by introducing signaling for trains in operation for on site workers controlling and notifying the networks flow. Also the 10 lifesaving rules educating employees increasing awareness around safety. Personally want to work for a company with high standards of safety as it shows how much they value the wellbeing of their employees and obviously I’d like to be safe at work :laugh emoji:
I also have experience adhering to safety standards in engineering teams around electrical systems from the time I worked on a renovation project in Pekham where I had to replace and install new power sockets in the flat. Using things such as circuit testers, the circuit breaker, insulated tools, power tools and spacial awareness, not having liquids by electronics, trunking exposed wire ect.
Diversity at network rail, and how you respected diversity in your own teams?
-Attracts prospective talent from all walks of life and backgrounds, not missing out on great recruitment opportunities
-Creates a comfortable environment for employees to shine and work to their fullest potential by seeing people from a similar background to them in leadership positions
-Maintains good customer relations especially in a place like London, anti-diversity practices would raise alarms in the society the company is meant to serve
-Flexible approach in meeting planning around religious obligations on Fridays and Sundays for some group members
