40 Questions
What is a diesel power station/DG Set?
A generating station in which diesel engine is used as the prime mover
What is the main reason why diesel power stations are only used to produce small power?
Due to high price of diesel
What is one of the advantages of diesel power stations?
It occupies less space as the number and size of the auxiliaries is small
Why are diesel power stations used as standby sets?
For continuity of supply to important points
What is a disadvantage of diesel power stations?
It has high running charges as the fuel used is costly
What is a characteristic of diesel power stations?
It can only generate small power
What is an advantage of diesel power stations over steam power stations?
The overall cost of diesel power station is less than that of steam power station of the same capacity
Why are diesel power stations used in areas where demand of power is less?
Due to transportation facilities being inadequate in these areas
Which type of battery is commonly used in UPS systems?
Lead Acid/Plante
What is the unit used to measure the required power of a battery?
Watts per cell
What is an important factor to consider when sizing a UPS system?
Power factor of the load
What is the purpose of redundancy in a UPS system?
To provide backup in case of a failure
What should be considered when selecting a UPS topology?
The application's sensitivity to power interruptions
What is an important consideration when selecting a battery type?
Energy density
Why is it important to consider the charging time of a battery?
To minimize downtime
What should be ensured when installing a UPS system?
That the UPS is compatible with the load characteristics
What is the purpose of the air intake system in a diesel power station?
To supply necessary air to the engine for fuel combustion
What is the primary function of the cooling system in a diesel power station?
To keep the temperature of the engine parts within safe operating limits
What type of generator is used in a diesel power station?
Synchronous generator
What is the purpose of the lubricating system in a diesel power station?
To minimize the wear of rubbing surfaces of the engine
What is the primary function of a UPS (Uninterruptible Power Supply)?
To maintain a continuous supply of electrical power in case of mains failure
What is the purpose of the excitation unit in a diesel power station?
To regulate the terminal voltage
What is the purpose of the fuel supply system in a diesel power station?
To supply fuel to the engine
What is the purpose of the exhaust system in a diesel power station?
To lead the engine exhaust gas outside the building and discharge it into the atmosphere
What is the primary function of a UPS?
To supply power to equipment during input power interruptions
What type of UPS is also known as a Standby UPS system?
Off-line UPS
What is the purpose of the tap-changing transformer in a Line Interactive UPS?
To provide voltage regulation
What is the advantage of an On-line UPS over an Off-line UPS?
It provides electrical isolation
What is the typical transfer time of an Off-line UPS?
25 milliseconds
What is the purpose of the rectifier in an On-line UPS?
To convert AC power to DC power
What is the disadvantage of an On-line UPS?
It is more costly due to the design of constantly running converters and cooling systems
What is the typical application of a Line Interactive UPS?
Small business and departmental servers
What is a crucial aspect to consider when selecting a battery bank?
Physical size and weight
Why is it essential to implement a battery monitoring system?
To monitor the battery's health and performance
What should be checked before selecting a battery bank?
The battery's warranty
Why is it important to ensure seamless integration between the UPS and battery banks?
To create a reliable and efficient backup power system
What is an essential safety measure to implement when using battery banks?
Proper ventilation
Why is it advisable to consult with a professional when selecting a UPS and battery bank?
To ensure the chosen system aligns with the specific requirements and constraints of the application
What is essential to ensure when selecting a UPS and battery bank?
Adherence to local codes and regulations
Why is it important to develop a testing and maintenance schedule?
To verify the functionality of both the UPS and battery banks regularly
Study Notes
Diesel Power Station (DG Set)
- A generating station that uses a diesel engine as the prime mover for generating electrical energy.
- The diesel engine drives an alternator, which converts mechanical energy into electrical energy.
- Advantages:
- Simple design and layout
- Occupies less space
- Can be located anywhere
- Quick start-up and load pick-up
- No standby losses
- Less water required for cooling
- Lower overall cost compared to a steam power station of the same capacity
- Higher thermal efficiency
- Requires less operating staff
- Disadvantages:
- High running charges due to costly fuel (diesel)
- Unsatisfactory performance under overload conditions for a long period
- Limited to generating small power
- High cost of lubrication
- High maintenance charges
Schematic Arrangement of Diesel Power Station
- Auxiliaries:
- Fuel supply system
- Air intake system
- Exhaust system
- Cooling system
- Lubricating system
- Engine starting system
- Diesel generator set: a salient pole type synchronous generator, self-excited and self-regulated by an excitation unit
Uninterruptible Power Supply (UPS)
- A device that maintains a continuous supply of electrical power, even in the event of a mains (utility) supply failure.
- Installed between the mains supply and the equipment to be protected.
- Uses: safeguarding computers, data centers, and critical equipment in large organizations.
- Working principle:
- Converts mains AC supply to DC voltage
- Charges batteries during normal operation
- Uses DC voltage from batteries to supply power during a mains failure
- Converts DC voltage back to AC voltage using an inverter
- Advantages: immediate protection against input power interruptions, short battery run time, and safe shutdown of connected equipment
Types of UPS
- Off-line UPS (Standby UPS system):
- Primary source is the filtered AC mains
- Transfer switch selects the backup source during a power breakage
- Least expensive UPS system, provides surge protection and backup
- On-line UPS:
- Double conversion method: AC input is converted to DC for storage, and then converted back to AC for the load
- Used where electrical isolation is mandatory
- More expensive due to the design of constantly running converters and cooling systems
- Line Interactive UPS:
- Used for small business and departmental servers
- Similar to off-line UPS, but with the addition of a tap-changing transformer for voltage regulation
- Provides additional filtering and lower transient loss
Battery Types
- Lead Acid/Plante Battery
- Lead Acid/Antimony Battery
- Lead Acid/Calcium Battery
- Lead Acid/Calcium, Maintenance-free Liquid Electrolyte Battery
- Lead Acid/Calcium, Maintenance-free Gelled Electrolyte, Sealed Battery
- Lead Acid (Special Alloy), Suspended Electrolyte, Maintenance-free, Sealed Battery
- Nickel Cadmium, Pocket Plate Liquid Electrolyte Battery
Battery Sizing
- Manufacturers provide sizing information for their batteries
- Battery sizing is typically done using watts per cell or amperes per cell
- Watts per cell method: uses kilowatts per cell tabulated for various backup times
- Amperes per cell method: uses charts expressed in available amps for specified periods of time
Selection of UPS and Battery Banks
- Key considerations:
- Power capacity (kVA or kW)
- Topology (Online Double Conversion, Line Interactive, Standby)
- Redundancy
- Scalability
- Efficiency
- Compatibility
- Monitoring and management
- Form factor
- Battery type (VRLA, lithium-ion)
- Capacity and autonomy
- Charging time
- Temperature considerations
- Maintenance requirements
- Footprint
- Monitoring system
- Warranty
- Integration and compatibility
- Safety
- Testing and maintenance schedule
A generating station that uses a diesel engine as the prime mover for generating electrical energy, offering advantages like simple design, quick start-up, and lower costs.
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