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Operation and Maintenance of Diesel Generators – Part 7: DG Starting Procedures, Do’s & Don’ts, and DG Efficiency Calculations

 Part 6: DG Starting Procedures, Do’s & Don’ts, and DG Efficiency Calculations

Operating a Diesel Generator (DG) set efficiently requires an understanding of the different starting modes, proper operational procedures, and maintenance best practices. Whether it's for routine operation or testing, knowing the correct procedures to follow ensures smooth performance and prevents costly repairs. The proper handling of the engine through manual, auto start, or test modes can also significantly enhance the generator’s longevity and fuel efficiency.

This seventh part of the Operation and Maintenance of Diesel Generators Series provides a detailed overview of DG starting procedures, key operational modes, and critical Do’s & Don’ts to follow for optimal performance. We also explore DG efficiency calculations, which are essential for tracking fuel consumption and understanding operational costs. These insights are valuable in ensuring reliable power supply, especially in critical applications.

If you haven’t read the previous parts, check them out here:

Part 1: Operation and Maintenance of Diesel Generators – Part 1: Understanding Diesel Engine, Its Working Principle and Key Components

Part 2: Operation and Maintenance of Diesel Generators – Part 2: Understanding Alternator, Its Components, and Working Principle

Part 3: Operation and Maintenance of Diesel Generators – Part 3: Understanding Starting system and Lubrication system of Diesel Generators

Part 4: Operation and Maintenance of Diesel Generators – Part 4: Understanding Fuel System and Air System of Diesel Generators

Part 5: Operation and Maintenance of Diesel Generators – Part 5: Understanding Cooling System of DG, Its Working Principle and Key Components

Part 6: Operation and Maintenance of Diesel Generators – Part 6: Understanding A-Check, B-Check, C-Check, and D-Check for Diesel Generators

Starting of DG Set

Modes for Starting a DG Set

A diesel generator set can be started using a battery through the following modes:

  1. Push Button (Manual Mode)

  2. Auto Start (Auto Mode)

  3. Test Mode (For Testing Purposes)

The operational mode is selected using a selector switch.

Push Button Start (Manual Mode)

  • Press the start push button and turn the ignition key to the start position.

  • The battery connects to the starter, cranking the engine shaft and initiating the start.

  • Commonly used in small DG sets.

  • Precaution: Do not push the start button for more than 10 to 12 seconds to avoid starter damage.

Auto Starting System (Auto Mode)

  • Used where a constant power supply is needed.

  • The DG set starts automatically in case of:

    • Mains failure.

    • Low/high mains voltage (below 150V or above 250V for single phase, below 360V or above 460V for three phase).

    • Single phasing or phase reversal.

  • Once the alternator reaches the preset voltage, the DG contactor closes and restores supply to the load.

  • If the DG set fails to start after three attempts, the system locks out.

  • After mains power is restored, the DG set runs for 3 minutes before shutting down to ensure stability.

Test Mode

  • Similar to manual mode.

  • The DG supply cannot be transferred to the load.

  • Used for testing the generator without transferring power.

Starting the DG Set - Step by Step

Before starting, perform daily maintenance checks:

  • Do not push the start button for more than 10-12 seconds.

  • Wait for 2 minutes between each attempt.

  • If the engine fails to start after three attempts, check the fuel system and fuel level.

  • Absence of blue or white exhaust smoke indicates no fuel is being delivered.

  • Move the ignition key from start to idle once the engine starts.

  • Monitor oil pressure and coolant temperature gauges.

Stopping the DG Set

  • Remove the load from the engine.

  • Run the engine for 3-5 minutes on no load before shutting down.

  • This allows lubricating oil and coolant to carry heat away from critical components.

  • Shut off the engine if oil pressure or coolant temperature exceeds limits.

  • Avoid continuous operation with low or high coolant temperature, as it may damage the engine.

Diesel Generator - Do’s & Don’ts

Do’s

  • Always idle the engine for 3-5 minutes before shutting down.

  • Monitor oil pressure (should indicate within 15 seconds of starting).

  • Maintain oil temperature between 75-105°C.

  • Maintain coolant temperature between 75-95°C.

  • Maintain normal engine pressure:

    • 105°C: 3-7 kg/cm² at rated speed.

    • Idle: 1-2 kg/cm².

Don’ts

  • Do not remove or open the fuel cap while the engine is running.

  • Do not overfill the fuel tank.

  • Do not add more oil than the FULL mark on the dipstick.

  • Do not operate the engine with loose or broken radiator belts.

  • Do not overtighten belts, as it increases wear.

  • Do not crank the engine for more than 10 seconds continuously.

  • If the engine fails to start after three attempts, check the fuel system.

Diesel Generator – DG Calculations

kWh/Diesel Calculation

Efficiency of a DG set is calculated using the kWh per liter formula:

  • Ideal: 3.6 kWh per liter.

  • Example:

    • Units generated in 1 hour: 1000 kW

    • Diesel consumption: 320 liters

    • kWh per liter: 1000 ÷ 320 = 3.1 kWh

Cost Per Unit Calculation

Formula: Cost per kWh = (Total Litre Consumption * Diesel Cost per Litre) ÷ kWh Generated

Example:

  • Total Litre Consumption: 320 L

  • kWh Generated: 1000

  • Diesel Cost per Litre: ₹60.20

  • Cost per kWh: (320 × 60.20) ÷ 1000 = ₹19.26

DG Efficiency Calculation

Step-by-Step Process

  1. Calculate Diesel Consumption (L).

  2. Calculate Diesel Output in kWh.

  3. Convert Diesel Consumption into BTU:

    • 1 Liter Diesel = 36500 BTU.

  4. Convert kWh into BTU:

    • 1 kWh = 3413 BTU.

  5. Calculate Efficiency:

    • Efficiency (η) = (Output Power in BTU) ÷ (Input Power in BTU).

Final Thoughts
The starting procedures, operational modes, and maintenance best practices discussed in this part are vital for the efficient and reliable operation of a Diesel Generator (DG) set. Following these guidelines ensures that the generator runs smoothly, reducing downtime and improving fuel efficiency. Furthermore, by understanding the DG efficiency calculations, you can track performance and optimize fuel consumption to ensure cost effective operation.

In the next part of our Diesel Generator Insights Series, we will delve into the DG efficiency calculations, including the kWh per liter formula, cost per unit calculation, and DG efficiency calculation, which are essential for tracking the performance and improving operational costs.

Got any questions or insights? Drop a comment below! If you found this article helpful, share it with others in the industry. Stay tuned for the next part!

Disclaimer
This article is for educational purposes only and has been compiled from various online sources. While every effort has been made to ensure accuracy, readers should refer to manufacturer guidelines and industry experts for specific operational and maintenance instructions. AI Generated Image is used in this Blog post.

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