How to Select and Configure Emergency Diesel Generators

 
The role of emergency diesel generators in modern critical facilities and important locations cannot be overlooked, especially in the event of sudden power outages or accidents. They are key devices in ensuring uninterrupted power supply during emergencies. Choosing the right emergency diesel generator not only affects system stability but also directly impacts the efficiency of fault recovery and the safety of load supply. This article will explore the selection and configuration of emergency diesel generators, covering aspects such as capacity selection, generator types, control systems, automatic start functionality, and special requirements for certain applications.

Capacity and Power Selection

 
Choosing the appropriate capacity for an emergency diesel generator is the foundation for ensuring effective power supply. In emergencies, the generator must have sufficient power to maintain the normal operation of all critical loads. According to standards, the rated capacity of the generator should be the 12-hour rated capacity after atmospheric correction, and it must meet the following requirements.

Total Emergency Load: The generator's capacity should support all emergency equipment's power requirements, ensuring the normal operation of critical systems.
High-Capacity Motor Startup: The generator must also handle the startup current of a large-capacity motor in the primary load. Therefore, when selecting a generator, it is essential to verify that the unit has sufficient power reserves during emergencies.

Common emergency diesel generators typically use three-phase AC synchronous generators with a rated output voltage of 400V. When multiple backup units are considered, usually only one generator is needed to meet the power demand of all loads. In specific cases, two generators may be paralleled to enhance reliability, but the total number of backup units should not exceed three.

Generator Type and Configuration

 
To simplify maintenance and improve system reliability, it is advisable to select emergency diesel generators of the same model and capacity, with similar voltage regulation and speed control characteristics. This ensures smooth transitions during parallel operation or switching between units and reduces compatibility issues. Additionally, the type of fuel used for the generators should be consistent, simplifying fuel management, storage, and supply.
 
When two generator units are configured, the emergency system should have mutual backup functionality. In the event of a power failure, the automatic start system should issue a start command after confirming the outage. If the first generator fails to start after three attempts, an alarm should trigger, and the second unit should automatically start to ensure uninterrupted emergency power supply.

Diesel Engine Selection

 
High-speed turbocharged diesel engines are an ideal choice for emergency diesel generators due to their efficiency and compactness. The advantages of these engines are as follows.
 
Large Single-Unit Capacity: High-speed turbocharged diesel engines offer large output power with a small footprint, making them suitable for projects with limited space.
Electronic Speed Control: Modern diesel generators are equipped with electronic speed control, allowing them to respond quickly to load changes, ensuring voltage and frequency stability and enhancing system reliability.
Brushless Excitation Synchronous Generators: These generators, with their brushless structure, significantly reduce maintenance costs and have a lower failure rate, making them more reliable in operation.
To minimize noise pollution, the exhaust system of diesel generators should be equipped with silencers to effectively reduce noise and ensure environmental comfort.

Control System and Automatic Start Functionality

 
The control system of an emergency diesel generator is crucial for ensuring a quick response, requiring fast self-start and automatic transfer functions. When the main power source fails, the generator should start and restore power within a few seconds to minimize downtime for critical equipment. Typically, the permissible outage time for primary loads ranges from several seconds to several tens of seconds, depending on the specific application.
 
After a power failure, the system should set a delay of 3-5 seconds to avoid unnecessary switching or false actions due to momentary voltage drops. This delay also allows for the instant recovery of the main power or automatic backup power engagement. The startup process for the diesel generator includes starting, speeding up, and load connection. For medium and large diesel engines, pre-lubrication and warm-up are necessary to ensure that key parameters (such as oil pressure, oil temperature, and coolant temperature) meet operational requirements before loading.

Multi-Unit Configuration and Parallel Operation

 
In certain situations, such as high-reliability locations or where large loads are present, using multiple generator units in parallel operation is a common solution. For parallel units, it is recommended to select equipment with the same model and capacity, and the voltage regulation and speed control characteristics should be similar to ensure power balance and stable operation during parallel use.
 
To simplify maintenance, the units should use the same parts and fuel, allowing for shared spare components and reducing the complexity and cost of repairs. In emergency situations, parallel operation of multiple units can significantly enhance system reliability and prevent power outages due to single-unit failure.

Special Requirements for Quick Start in Critical Situations

 
In high-reliability environments, such as military communication facilities, major hotel events, or surgical operations in hospitals, emergency generators must be in a pre-lubricated and warm-up state to ensure instant startup and rapid power restoration when the main power fails. These critical loads cannot tolerate extended power outages, making quick response capability crucial.
 
In such cases, diesel generators are typically kept in a preheated state to ensure that key operational parameters are met at startup, further reducing the startup time and ensuring seamless power continuity.
 
Choosing an emergency diesel generator involves several key factors, including capacity, type, control system, and configuration. By selecting high-speed turbocharged diesel engines, control systems with quick start capabilities, and ensuring consistency in equipment models and fuel types, the reliability of the emergency power system can be significantly improved. For applications requiring high reliability, parallel unit operation and quick start configurations offer additional protection. In summary, a well-selected and configured emergency diesel generator provides stable and efficient power support, ensuring rapid recovery and continuous operation in emergency situations.