40 Questions
What is the primary source of mechanical energy in a diesel power station?
The combustion of diesel
Why are diesel power stations used in certain areas?
Because the demand for power is less in those areas
What is a major disadvantage of diesel power stations?
They have high running charges due to costly fuel
What is an advantage of diesel power stations in terms of location?
They can be located at any place
What is a characteristic of the design and layout of a diesel power station?
They are simple and occupy less space
Why are diesel power stations used as standby sets?
Because they can provide continuity of supply to important points
What is a benefit of diesel power stations in terms of water usage?
They require less quantity of water for cooling
What is a limitation of diesel power stations in terms of power generation?
They can only generate small power
What is the primary function of a UPS?
To offer immediate protection against 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 additional filtering and reduce transient loss
What is the primary advantage of an On-line UPS?
Zero transfer time
What is the function of the rectifier in an On-line UPS?
To convert AC input to DC
What is the primary disadvantage of an Off-line UPS?
Long transfer time
What is the purpose of the power inverter in a UPS?
To convert DC to AC
What is the advantage of a UPS over other immediate power supply systems?
Immediate protection against power interruptions
What is the primary function of the fuel supply system in a diesel power station?
To store and pump fuel oil to the engine at regular intervals
What is the purpose of the filters in the air intake system of a diesel power station?
To remove dust particles from the air which may act as abrasive in the engine cylinder
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 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 the engine starting system in a diesel power station?
To rotate the engine initially until firing starts
What is the purpose of the choke in the excitation unit of an alternator?
To adjust the terminal voltage at no load
What is the primary function of a UPS (Uninterruptible Power Supply)?
To maintain a continuous supply of electrical power during a mains failure
What is the purpose of the rectifier in a UPS?
To convert AC to DC voltage
What is a crucial consideration when selecting a battery bank?
The physical size and weight of the battery
What is the primary purpose of a battery monitoring system?
To track the health and performance of the batteries
Why is it essential 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 a key aspect of ensuring overall system safety?
Proper ventilation for batteries
What is the primary benefit of developing a testing and maintenance schedule?
To verify the functionality of both the UPS and battery banks regularly
What is a crucial consideration when selecting a battery bank, in terms of replacement costs?
The warranty provided by the battery manufacturer
Why is it essential to ensure compatibility between the UPS and battery banks?
To create a reliable and efficient backup power system
What is a key consideration when selecting a UPS and battery bank, in terms of compliance?
Adherence to local codes and regulations
What is the typical room temperature assumed by manufacturers for providing sizing information for their batteries?
25oC
Which of the following battery types is commonly used in UPS systems due to its energy density and cycle life?
Lithium-ion Battery
What is the unit used to measure the power capacity of a UPS?
kVA or kW
What is the primary consideration for selecting a UPS topology?
Application's sensitivity to power interruptions
What is the formula used to calculate the required Amperes per cell for lead acid batteries designed for short discharge times?
Amperes = VA × pf × η × N + Al
What is the factor that affects the battery capacity and autonomy during a power outage?
Desired autonomy period
What is the purpose of considering redundancy in UPS systems?
To provide backup in case of a failure
What is the advantage of selecting a UPS system with advanced monitoring and management features?
It provides remote monitoring, diagnostics, and alerts
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
Test your knowledge of diesel power stations, including their design, advantages, and operation. Learn about the mechanical and electrical components involved in generating electrical energy.
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