Views: 0 Author: Site Editor Publish Time: 2011-05-05 Origin: Site
1)The performance and quality of the selected diesel generator set must meet the requirements of relevant standards
Diesel generators are widely used as emergency backup power sources in telecommunications, financial departments, hospitals, schools, commerce and other departments, industrial and mining enterprises and residences, as well as independent power sources for military and field operations, vehicles and ships.
As a diesel generator set for communication, it must meet the requirements of G3 or G4 in GB2820-1997, and at the same time, it must meet the 24 performance index requirements specified in the 'Implementation Rules for Network Quality Certification and Testing of Diesel Generators for Communication', and must pass the Strict inspection by the Communication Power Equipment Quality Supervision and Inspection Center established by my country's industry authorities.
As a diesel generator set for military communications, it must meet the relevant GB2820-1997, GJB relevant standards and the 'Quality Inspection Standards for Communication Power Equipment' formulated by relevant military departments, and must pass the strict inspection of equipment quality by relevant organizational departments.
2)Main factors to consider when choosing a diesel generator set
Factors that should be considered when selecting a unit include mechanical and electrical performance, purpose of the unit, load capacity and variation range, automation functions, etc.
Purpose of the unit.Because diesel generator sets can be used in three situations: regular use, backup and emergency.Therefore, different uses have different requirements for diesel generator sets.
load capacity.The load capacity and load variation range should be selected according to different uses, and the single unit capacity and backup diesel generator capacity of the diesel generator set should be determined.
The operating environment conditions of the unit (mainly refers to altitude and climate conditions)
Diesel generator selection
Selection of generator and excitation methods
Selection of automation functions for diesel generators
The 24 performance index requirements stipulated in the Implementation Rules for Network Quality Certification and Inspection of Diesel Generators for Telecommunications:
Appearance requirements
The boundary dimensions, installation dimensions and connection dimensions of the diesel generator set are in compliance with the factory drawings approved by the prescribed procedures.
The welding of the unit should be firm, the welds should be uniform, and there should be no defects such as weld penetration, undercuts, slag inclusions, and pores. The welding slag and flux should be removed cleanly; the paint film should be uniform without obvious cracks and peeling; the coating should be smooth and free of leaks. Plating spots, rust and other phenomena; the fasteners of the unit should not be loose.
The electrical installation of the diesel generator should comply with the circuit diagram, and the connection points of each wire of the unit should have obvious signs that are not easy to fall off.
Diesel generators should have well-grounded terminals.
Diesel generator signage is complete (Copyright © WWW.HXDLKJ.COM)
Insulation resistance and insulation strength
Insulation resistance: The insulation resistance of each independent electrical circuit to ground and between circuits should be greater than 2M
Insulation strength: Each independent electrical circuit of the unit should be able to withstand the AC test voltage for 1 minute to ground and between circuits, and there should be no breakdown or flicker.
| loop voltage | Test voltage |
| <100V | 750V |
| ≥100V | 1440V |
Phase sequence requirements.The phase sequence of the terminals on the control panel of the diesel generator set should be arranged from left to right or top to bottom when viewed from the front of the control panel.(Copyright © WWW.HXDLKJ.COM)
Diesel generators are required to maintain readiness for operation.The unit should have a heating device to ensure that the oil temperature and cooling medium temperature during emergency start and rapid loading are not lower than 15°C.
Reliability check of automatic power supply and automatic shutdown
After receiving the starting command from the automatic control or remote control, the diesel power generation should be able to start automatically.
When the unit fails to start automatically for the third time, a start failure signal should be sent; when a backup unit is provided, the program startup system should be able to automatically transmit the start command to another backup unit.
The time from the automatic start command to supplying power to the load should not exceed 3 minutes.
After the diesel generator automatically starts successfully, the loading capacity should not be less than 50% of the calibrated load.
After receiving a shutdown command from automatic control or remote control, the unit should be able to stop automatically; for a standby unit used in conjunction with the mains power grid, when the power grid returns to normal, the diesel generator should be able to automatically switch or stop automatically, and its shutdown method and shutdown delay time should comply with Product technical conditions.
Automatic startup success rate.The automatic startup success rate is no less than 99%.
No-load voltage setting range requirements.The no-load voltage setting range of the unit shall not be less than 95%-105% of the calibrated voltage.
Auto-replenishment feature requirements.The unit should be able to charge the starting battery automatically.(Copyright © WWW.HXDLKJ.COM)
Automatic protection function requirements.The unit should be protected against phase loss, short circuit (not greater than 250KW), overcurrent (not greater than 250KW), overspeed, high water temperature and cylinder temperature, and low oil pressure.
Line voltage waveform sinusoidal distortion rate.Under the no-load calibration voltage and calibration frequency, the sinusoidal distortion rate of the line voltage waveform is <5%.
Voltage steady-state adjustment rate ≤250KW >250KW 3% 2%
Voltage transient regulation rate ≤250KW >250KW 20% 15%
Voltage stabilization time ≤250KW >250KW ≤2s ≤1.5s
Voltage fluctuation rate≤250kw >250kw 0.8% 0.5%
Frequency steady-state adjustment rate ≤250kw >250kw 3% 3%
Frequency transient adjustment rate ≤250kw >250kw 9% 9%
Frequency stabilization time ≤250kw >250kw 5s ≤5s
Frequency fluctuation rate ≤250kw >250kw ≤0.8% ≤0.5%
Voltage deviation under three-phase asymmetric load: When a diesel generator set is under a three-phase symmetrical load of 25%, and a resistive load of 25% of the calibrated phase power is added to any phase, the unit should be able to operate normally. The maximum or minimum line voltage and 5% of the average value of the three-wire voltage.
The average noise sound pressure at a distance of 1m from the diesel engine and generator of the unit:
≤250KW >250KW
≤102db(A) ≤108db(A)
Sleep <45db Environmental noise in residential areas should not exceed 50 decibels during the day and should be less than 45 (40) decibels at night
Work <65 db. The average person can maintain normal reactions and attention under a sound of about 40 decibels. However, if you work in an environment above 50 decibels for a long time, you will suffer from hearing loss, emotional irritability, and even neurasthenia. and other phenomena.
Listening to music 80db Children living in an environment with noise above 80 decibels can cause deafness in up to 50% of people. Only when the noise level is below 80 decibels can people maintain long-term work without deafness for 40 years; at 100 decibels, only 60% of people will not be deafened. Will be deaf.If people live in an environment above 80 decibels for a long time, it will cause emotional irritability and hearing loss.Noise is harmful to people and can induce cardiovascular system diseases. When eating in a strong noise environment, gastrointestinal capillaries will shrink, the secretion of digestive juices and gastrointestinal peristalsis will be weakened, and the normal blood supply will be affected. destroy.Intense noise can also cause pregnancy abnormalities and intellectual development disorders in children.Therefore, we should try to reduce the source and spread of noise as much as possible in our daily life.
Below 85 decibels can cause slight hearing damage;
85 dB-90 dB can cause noise-induced deafness in a small number of people;
90-100 decibels can cause noise-induced deafness in an appropriate amount;
Above 100 decibels, a considerable amount of noise-induced deafness will occur, which are classified as chronic noise-induced deafness.
Above 105 decibels --- 5 minutes
Fuel consumption.The calibrated power of the unit is within the range of 120<600kW, and the fuel consumption rate is ≤260G/KW.H
Diesel generator consumption rate.Calibrated unit power >40KW, unit consumption rate ≤3.0G/KW.H
Operation of the test unit under calibrated working conditions Under the specified working conditions (section 4.2 in GB2820), the unit can operate normally and continuously for 12 hours under the calibrated working conditions (including 1 hour of overload operation at 10%), and the diesel generator set should have no water leakage and air leakage.
Remote control, telesignaling and telemetry performance
Intelligent unit
Units above 200KW should be intelligent, and their monitoring content and interface requirements are as follows:
①Remote control: turn on/off, emergency stop, switch between main and backup units.(Copyright © WWW.HXDLKJ.COM)
②Remote signaling: working status (running/stop), working mode (automatic/manual), main units, overvoltage, undervoltage, overcurrent, frequency
③Remote measurement: three-phase output voltage, three-phase output battery voltage, and output power.
④Interface: It should have communication interface (RS-232 and RS-485/422) and be able to provide a complete communication protocol.
Non-intelligent unit
Non-intelligent units of 200KW and below do not have remote control, remote signaling and telemetry requirements.
Emergency diesel generators are mainly used in important places. In the event of an emergency or accidental power outage, the emergency generator set can quickly restore and extend the power supply for a period of time.This type of electrical load is called a primary load.Equipment, instruments and computer systems that have strict requirements on power outage time should be equipped with batteries or UPS in addition to generators.
The work of emergency diesel generators has two characteristics: the first characteristic is for emergency use, the continuous working time is not long, and generally only needs to run continuously for a few hours (≤12H); the second characteristic is that it is used as a backup, emergency generator set It is usually in a shutdown waiting state. Only when the main power supply is completely out of power, the emergency diesel generator set will start to operate to supply the emergency power load. When the main power supply returns to normal, it will switch to shutdown immediately.
Determination of emergency diesel generator generator capacity
The calibrated capacity of the emergency diesel generator set is the 12-hour calibrated capacity corrected by the atmosphere. Its capacity should be able to meet the emergency total calculated load, and should be verified based on the generator capacity that can meet the requirements for starting a single maximum capacity motor in the first-level load. .Emergency generators generally use three-phase AC synchronous generators with a calibrated output voltage of 400V.
Determination of the number of emergency diesel generator sets
When there are multiple generator sets on standby, generally only one emergency diesel generator set is installed. For reliability reasons, two units can also be connected in parallel for power supply.The number of generator sets for emergency use should generally not exceed 3.When multiple units are selected, the units should try to use complete sets of equipment with the same model, capacity, and similar pressure and speed regulation characteristics. The properties of the fuel used should be consistent to facilitate maintenance and sharing of spare parts.When there are two generator sets supplying emergency needs, the self-starting device should enable the two units to serve as backup for each other. That is, after the mains power failure and power outage are delayed and confirmed, a self-start command will be issued. If the first unit self-starts three times in a row, If starting fails, an alarm signal should be sent and the second diesel generator should be started automatically.
Emergency diesel generator selection
The emergency unit should choose a diesel generator set with high speed, supercharging, low fuel consumption and the same capacity.The high-speed supercharged diesel engine has a larger single unit capacity and takes up less space; the diesel engine should be equipped with an electronic or hydraulic speed regulating device, which has better speed regulating performance; the generator should be a synchronous motor equipped with a brushless excitation or phase compound excitation device, which is more reliable and prevents faults. The efficiency is low, and maintenance and inspection are more convenient; when the capacity of a single air conditioner or the capacity of the motor in the primary load is large, a generator set with third harmonic excitation should be selected; the unit is assembled on a common chassis with a shock absorber; smoke exhaust A muffler should be installed at the pipe outlet to reduce the impact of noise on the surrounding environment.
Control of emergency diesel generator set
The control of the emergency generator set should have fast self-starting and automatic input devices.When the main power supply fails and the power is cut off, the emergency unit should be able to quickly self-start and restore power supply. The allowable power outage time for the primary load ranges from more than ten seconds to tens of seconds and should be determined according to the specific situation.When the main power supply of an important project is cut off, a certain time of 3-5 seconds should be passed to avoid the instantaneous voltage drop and the time when the municipal power grid is closed or the backup power supply is automatically put in, before issuing an instruction to start the emergency generator set.It takes some time from the time the command is issued, the unit starts to start, and the speed increases until it can carry full load.Generally, large and medium-sized diesel engines also need pre-lubrication and warm-up processes to ensure that the oil pressure, oil temperature, and cooling water temperature during emergency loading meet the specifications of the factory's technical conditions; the pre-lubrication and warm-up processes can be carried out in advance according to different situations.For example, emergency units in military communications, important foreign affairs activities in large hotels, large-scale mass activities in public buildings at night, and important surgeries in hospitals should be in pre-lubricated and warm-up states at ordinary times so that they can be started quickly at any time and minimize the time of power outages. .(Copyright © WWW.HXDLKJ.COM)
After the emergency unit is put into operation, in order to reduce the mechanical and current impact when the load is suddenly added, the emergency load should be increased in stages according to time intervals as much as possible while meeting the power supply requirements.According to the national standards and national military standards, the allowable loading capacity of the automated unit after successful startup is as follows: for those with a calibrated power not greater than 250KW, the allowable loading capacity is not less than 50% of the calibrated load; for those with a calibrated power greater than 250KW, the allowable loading capacity is based on the manufacturer's technology Conditions stipulate.If the requirements for instantaneous voltage drop and transition process are not strict, the sudden load addition or unloading of the general unit should not exceed 70% of the unit's calibrated capacity.
Some diesel generator sets need to be operated continuously for a certain period of time or often for a long time to serve as a common power supply for electrical loads. This type of generator set is called a common generator set.The common generator set can be used as a common generator set and a backup generator set.In order to supply local residents with electricity for production and daily life, diesel generators need to be installed in towns, islands, forest farms, mines, oil fields and other areas or industrial and mining enterprises that are far away from large power grids. Such generators should be operated uninterrupted at ordinary times.
Important facilities such as national defense projects, communication hubs, radio stations, and microwave relay stations should be equipped with backup diesel generator sets.When such facilities use electricity, they can be supplied by the mains power grid.However, after the municipal power grid is damaged and causes a power outage due to earthquakes, typhoons, wars and other natural disasters or man-made factors, the backup units that have been set up should be started quickly and continue to operate uninterrupted for a long time to ensure the power consumption of these important projects. Continuous power supply to the load, this kind of standby generator set is also a common type of generator set.Commonly used generator sets have long working hours and large load curve changes. The selection of unit capacity, number, type and unit control method are different from emergency units.
Determination of the capacity of commonly used diesel generator sets
The output power of the unit in long-term continuous operation can meet the maximum calculated load of the entire project, and the backup unit capacity of the generating unit should be determined according to the importance of the load.The continuous output power of the diesel engine is generally 0.9 times the calibrated power.
Determination of the number of commonly used diesel generator sets
The number of commonly used diesel generator sets is usually more than 2 to ensure the continuity of power supply and adapt to changes in the power load curve.Only with a large number of units can the number of generator units invested can be determined according to changes in electrical load, so that the diesel engine can often run under economic load to reduce fuel consumption and power generation costs.The economic operating state of the diesel engine is between 75% and 90% of the rated power.In order to ensure the continuity of power supply, the commonly used unit itself should consider setting up a backup unit. When the unit is faulty or shut down for inspection, the generator set can still supply power to important electrical loads without interruption.
Determination of the speed of commonly used diesel generator sets
In order to reduce wear and increase the service life of the unit, commonly used generator units should choose medium or low-speed units with a calibrated speed of no more than 1000r/min. The backup unit can choose medium or high-speed units.Units in the same power station should use units of the same model and capacity so that they can use the same spare parts and facilitate maintenance and management.For projects with large load changes, units of the same series with different capacities can also be selected.The determination of the generator output calibration voltage is the same as that of the emergency generator set, which is generally 400V. High-voltage generator sets can be used for projects with large power consumption and long transmission distances.
Control of commonly used diesel generator sets
Commonly used units should generally be considered to be connected in parallel to simplify the main wiring of power distribution, so that when the units start and stop in rotation, the power supply will not be interrupted by parallel operation, load transfer, and unit switching.The unit should be equipped with unit measurement and control devices, and the speed regulation and excitation adjustment devices of the unit should meet the requirements for parallel operation of fish.For standby generator sets that supply power to important loads, it is advisable to use automated diesel generator sets that can quickly and automatically start to restore power to important loads after an external power failure.There is a lot of noise in the room when the diesel engine is running, and the automated unit can be easily transformed into a generator set with compartment operation and automatic monitoring.When the generator set is running normally, the operator does not need to enter the diesel engine room and can monitor the diesel generator set in the control room.(Copyright © WWW.HXDLKJ.COM)
After making the above selections, the order for the diesel generator set should generally indicate the following:
Unit model, rated power, rated frequency, rated voltage, rated current, number of phases, power factor and wiring method, etc.
Requirements for unit automation functions and performance.
Requirements for the structure, performance and installation dimensions of diesel engines, generators and control panels.
Requirements for parallel operation of units: When purchasing multiple units at the same time, do you need to run them in parallel? If so, you should also ask whether you need to provide the measuring instruments and devices required for parallel operation.
Requirements for ancillary equipment of the unit: Many domestic manufacturers count cooling water tanks (radiators), fuel tanks, exhaust mufflers, batteries, etc. as ancillary equipment. Some installation requirements are allowed when ordering.
