Diesel Turbocharger proper use and maintenance

Diesel engine is mainly adopts gas turbocharged methods to improve its effective power. The turbocharger offset some of the natural aspirated engines congenital deficiency, not changing the cylinder diesel engine volume of cases greatly improve output power, so many engineering machinery had adopted the same turbocharged diesel enginetechnology to improve the output power, enhancing the quality of engine power than the high performance, realize the machine

1, turbocharger composition and function

Diesel engine cylinder by fuel burning in the energy input by fuel and air inhaled cylinders's limited amount of the power generated by also restricted, if the performance of the diesel engine is already at its best, add the output power can only through compressed more air into the cylinder to increase fuel, increase the combustion doing work ability. In the present technical conditions, turbochargers is the only one who can make the diesel engine in work efficiency under the condition of invariable increase the output power of mechanical device.

Turbocharged diesel turbochargers is the key parts, can increase the diesel engine power output by 20% ~ 30% and reduce fuel consumption, 8%, exhaust 25% ~ 50% FSN reduce the harmful poisonous gas, waste gas content is also significantly decrease. So in engineering machinery for daily use, paying attention to turbocharger proper use and maintenance to reduce the cost, reduce energy consumption and environmental protection to have the important meaning.

Turbochargers is actually a kind of air compressor, through the compressed air to increase the subsystem, and it mainly consists of turbine and compressor two parts. Turbine room inlet and exhaust manifold are linked together, then in the vent exhaust;Compressor with the inlet air filter, vent pipe connected up in intake manifold; Turbine impeller and compressor impeller are installed in turbine room and the supercharger inside, both coaxial rigid connection.

The turbocharger use diesel emissions inertial impact to drive the turbine indoor turbine, turbine and drive coaxial impeller, impeller press send brought by the air filter pipe, air pressurization into cylinder. When diesel engine speed, the waste gas discharge added fast speed and turbine speed increasing quickly, the impeller and synchronization is compressed more air into the cylinder, air pressure and density increases can burn more fuel, a corresponding increase in fuel and adjust the diesel engine speed, then increase the output power of diesel engine.

2, common fault analysis

The turbocharger installed in diesel engine exhaust manifold, at high temperature and high pressure and high speed running work condition, the working environment is very bad, work requirement and is hard, in use prone to failure. After the failure of the general expression for the power diesel drops greatly, and smoke when blue smoke and oil consumption is overmuch, supercharger abnormal voice, large noise. The main cause of fault for bad lubrication, foreign material into the and accumulation, fatigue damage.

(1) bad lubrication

Refers to the supercharger impeller and turbines in turbine compressor rotor shaft bearing not good lubrication, and rotor shaft and bearing damage, the supercharger doesn't work. Bad lubrication mainly by lubricating oil shortage, lubricating oil pipeline leak and caused fluid oil.to. 

(2) foreign material into and accumulation

Refers to the inlet pipe in dirt and exhaust duct microactivity, the accumulation of dust, sundry etc, if intake pipe air filter long-term replacement in the intake manifold, compressor impeller, and other long term not cleaning will produce coke, making intake resistance increases, the same turbine turbine and nozzle ring microactivity, also can produce adverse consequences. In addition, the exhaust system within the leak will also affect the normal work of the supercharger.

Generator Sizing and Ratings

Rating

Generators must be capable of delivering the power required for the hours per year anticipated by the designer to allow reliable operation and prevent damage. Typically a given set can deliver more power for fewer hours per year, or less power continuously. That is a standby set is only expected to give its peak output for a few hours per year, whereas a continuously running set, would be expected to give a somewhat lower output, but literally continuously, and both to have reasonable maintenance and reliability.

To meet the above criteria manufactures give each set a rating based on internationally agreed definitions.

These standard rating definitions are designed to allow correct machine selection and valid comparisons between manufacturers to prevent them from misstating the performance of their machines, and to guide designers.

Generator Rating Definitions

Standby Rating based on Applicable for supplying emergency power for the duration of normal power interruption. No sustained overload capability is available for this rating. (Equivalent to Fuel Stop Power in accordance with ISO3046, AS2789, DIN6271 and BS5514). Nominally rated.

Typical application - emergency power plant in hospitals, offices, factories etc. Not connected to grid.

Prime (Unlimited Running Time) Rating: Should not be used for Construction Power applications. Output available with varying load for an unlimited time. Average power output is 70% of the prime rating. Typical peak demand 100% of prime-rated ekW with 10% of overload capability for emergency use for a maximum of 1 hour in 12. A 10% overload capability is available for limited time. (Equivalent to Prime Power in accordance with ISO8528 and Overload Power in accordance with ISO3046, AS2789, DIN6271, and BS5514). This rating is not applicable to all generator set models.

Typical application - where the generator is the sole source of power for say a remote mining or construction site, fairground, festival etc.

Base Load (Continuous) Rating based on: Applicable for supplying power continuously to a constant load up to the full output rating for unlimited hours. No sustained overload capability is available for this rating. Consult authorized distributor for rating. (Equivalent to Continuous Power in accordance with ISO8528, ISO3046, AS2789, DIN6271, and BS5514). This rating is not applicable to all generator set models

Typical application - a generator running a continuous unvarying load, or paralleled with the mains and continuously feeding power at the maximum permissible level 8760 hours per year. This also applies to sets used for peak shaving /grid support even though this may only occur for say 200 hour per year.

As an example if in a particular set the Standby Rating were 1000 kW, then a Prime Power rating might be 850 kW, and the Continuous Rating 800 kW. However these ratings vary according to manufacturer and should be taken from the manufacturer's data sheet.

Often a set might be given all three ratings stamped on the data plate, but sometimes it may have only a standby rating, or only a prime rating.

Sizing

Typically however it is the size of the maximum load that has to be connected and the acceptable maximum voltage drop which determines the set size, not the ratings themselves. If the set is required to start motors, then the set will have to be at least 3 times the largest motor, which is normally started first. This means it will be unlikely to operate at anywhere near the ratings of the chosen set.

Steps for maintain the fuel injection pump of diesel engine

Fuel injection pump is an important component of fuel supply system in diesel engine, so its working status affect diesel engine reliably, economically and dynamically. Correct maintenance is an important precondition to insure injection pump working normally and extend its lifetime. So here we listed ten steps summed up from our experiences for your reference.

1、To monitor filtering process strictly to ensure the diesel going into injection pump is highly clean.

General speaking, diesel filtering is more strict than gasoline filtering process, so we must choose one brand which is suitable for requests and deposit at least 48hrs. strengthening maintenance and cleaning of diesel filter, replacement or cleaning timely；Washing fuel tank and removing the fuel deposit and water according to working condition, any impurity in diesel will cause pump jam and abrasion or corrosion of driving parts and fuel valve.

2、To check the oil quality and level of oil pool often

It is necessary to check oil level and quality of oil in injection pump every time we start generator sets except that engine forced lubrication, if oil goes bad by mixing with water, the lighter aftermath will cause jams and abrasion of oil vavle and lower power of engine and starting hardly. The heavier aftermath is to corrode oil valve. Meanwhile those problems like inner leakage of pump, oil valve working status and sealing ring breakage will let diesel go into oil for dilution, so it becomes very important to replace oil and wash oil pool wholly and remove impurities like oil deposit in order to avoid oil going bad again.

3、To regularly examine and adjust the fuel supply advance angle of fuel injection pump and oil supply interval angle of each cylinder.

Loose coupling bolts and abrasion of camshaft and rollers often lead to change of fuel supply advance angle and the cylinder oil interval angle, which make diesel go bad, accordingly causing deterioration of diesel combustion and economic nature, difficulty in starting, instable running, abnormal noise and overheat etc.. in practice most people only examine and adjust the overall fuel supply advance angle, but ignore examination and adjustment of the oil interval angle (involving adjustment of a single pump fuel supply advance angle ), doing that benefits fuel supply timely in first cylinder, but it is hard to ensure fuel supply timely in other cylinders because of arbasion of camshaft and roller components , so that difficult starting-up, power shortage and running unsmoothly, so it is very important to examine and adjust interval angle, especially for those used for long time.

4、To examine and adjust oil supply of each cylinder periodically.

Fuel leakage caused by abrasion of plunger and coupling valve will reduce oil supply or unevenly. Accordingly causing difficulty in starting, power shortage, increased fuel consumption and instable operation. Therefore, we should regularly examine and adjust the oil supply volume of each cylinder to ensure engine work effectively. In practice, we can determine oil supply volume of each cylider by observing the diesel smoke, listening to the engine noise and touching exhaust manifold temperature.

5、To exmaine clearance of camshaft regularly.

Axial clearance of camshaft is controlled between 0.03～0.15mm strictly, if the gap is too large, it will aggravate the impact of the work surface imposed by driving components,thereby increasing the early abrasion of cam surface and changing Oil advance angle; another hand, if the gas is too large, it could aslo lead to camshaft operating unsmoothly and fuel adjustment rod jitter,accompanying problems like periodic changes in fuel supply so that engine operation is unstable, therefore we should regularly examine and adjust clearance of camshaft. If axial clearance of camshaft is too large, we can add the pads on both sides to adjust it, if the radial clearance is too large, we usually need to replace a new one.

6、To examine the seal condition of coupling parts of outlet valve regularly.

We can make rough judgements on abrasion of plunger and working status of pump by checking seal condition of outlet oil vavle. Which will help determine the method of repair and maintenance. when inspection, We should twist the high-pressure oil pipe joints of each cylinder and use hand pump to pump oil, if we found that there was oil outlet at the top of the pipeline joints, it proves that the seal of outlet valve is not good, (of course a broken valve spring will cause same problem), if multi-cylinders have same problem, then a thorough commissioning and maintenance should be conducted, or even replacement of coupling parts.

7、To use standard high-pressure oil pipeline

high-pressure diesel will be the formation of pressure fluctuation in the pipe during fuel supply process due to the compressibility of diesel and flexibility of high-pressure oil pipeline, and the pressure wave in the pipe will take some time to pass, the length and diameter of high-pressure pipeline are measured and selected in order to ensure oil supply interval angle of each cylinder unanimously and fuel supply evenly and diesel engine working steadily, Thus, when one high-pressure pipeline is damaged, we should replace it by standard one. In actual use, we usually don’t consider length and diameter of pipeline so that there are big differences between length and diameter, although it can be as emergency use, but it will change oil supply advance angle and volume of oil supply so that the whole machine work instably, so we must use standard high-pressure pipeline.

8、To examine abrasion condition of relevant keyway and fixed bolts.

Related keyway and bolts mainly refer to the camshaft keyway, coupling flange keyway (oil pump to use coupling to transfer power ), semi-circular keys as well as coupling fixed bolts. due to long-term usage of camshaft keyway of injection pump and flange keyway and semi-circular key, the lighter aftermath is abrasion and keyway boardening and semi-circular keway installation insecurely and change of fuel supply advance angle; the severer case is key sub-rolled, resulting in power transfer failure, therefore we should regularly check, repair and replace worn parts.

9、To replace worn plungers and coupling parts of oil outlet valve timely

When we found problems like difficulty in starting diesel engines, power down and fuel consumption increased, we should dismantle plunger of injection pump and coupling parts of oil outlet valve if it can not be improved by by adjusting the fuel pump and injector, they should be promptly replaced if plunger and outlet valve are worn to a certain level, and do not insist on using any more.

10、To maintain accessories of injection pump in right way.

We must ensure Pump side covers, oil-foot, fuel plug (respirator), oil spill valve, oil tank screw block, oil flat screws, oil pump bolts intactly, these accessories play very important role in work performance of injection pump, eg. the side cover prevent intrusion of dust, moisture and other impurities, respirator (with filter) can effectively prevent oil deterioration, oil spill valve ensure the fuel system has a certain pressure to stop air going into. therefore we must strengthen maintenance of these accessories, and it must be promptly reparied or replaced once we discovered damage or loss.

Sensor overhaul of cummins diesel engine

Sensor overhaul of Cummins diesel engine

CM800 Type fuel system is a new type of control system of Cummins diesel engine, the system’s main function is to fuel supply and timing control. Here we elaborate the function and analyse the overhaul of sensor.

1. Coolant temperature sensor of Cummins diesel engine 
the sensor of diesel engine is lated in the right-front side of cylinder, whose function is to control the fan rotate, adjust the starting fuel supply, control injection timing and engine protection. Diesel engine run ranging between -40 ~ 140 °C. Sensor failure will lead to lower engine speed and power down, and difficulty in starting, diesel engine will shut down if the protection function ofCummins diesel engine is open.

The temperature sensor of Cummins diesel engine use two-wire thermal sensor, two-wire sensor is provided with two wires which have a power line and back line. Thermal resistance means that the resistance value will decline with temperature increasing. Therefore, we can use AVO meter to test resistance value of line plug of temperature sensor and compare with normal value to judge if the temperature sensor is working normally or not. Here list the normal range of parameters of temperature sensor, which is applicable to other temperature sensor of all Cummins diesel engine range.

Cummins diesel engine temperature sensor range of the normal parameters (fit all Cummins systems)
Sensor temperature °C – Resistance °C
0 – 5000 ~ 7000
25 – 1700 ~ 2500
50 – 700 1000
75 – 300 ~ 400
100 – 150 ~ 220

2. Fuel temperature sensor of Cummins diesel engine 
the sensor is installed on the top of inner shell of the fuel filter. Its function is to control fuel heater and protect Cummins diesel engine through sensor signal. Its working range -40 ~ 140 °C °C. Sensor failure will affect the engine performance. And the maintenance method is same as coolant temperature sensor.

3. Air pressure sensor of Cummins diesel engine 
the sensor is installed in ECM800 of diesel engine. Its function is to make use of the sensor signals to determine the current atmospheric pressure. The sensor cannot be maintained due to installation in ECM. Any problem must be met by Cummins service engineer.

4. Speed sensor of Cummins diesel engine (crankshaft speed sensor)
The sensor is installed in the front gear shell of diesel engine, its function is to test pulse signals and calculate engine speed and control oil supply of diesel engine. Sensor failure of Cummins diesel engine will cause power shortage, unstable idle speed, emission of white smoke, difficulty in starting or shutdown.

Cummins diesel engine speed and position sensors
Temperature (°C), temperature (℉), resistance (Europe)
-30, -22,688
20,68,860
50,122,963

Hall-effect speed and position sensors cannot be detected by measuring the resistance. We can test its output signals volt to judge the working performance by cranking Cummins diesel engine. During cranking Cummins diesel engine, the normal work of Hall-effect speed sensor output voltage range between 0V ~ 5V (0V and 5V for the nominal voltage, the actual voltage higher than 0V, slightly lower than 5V).

The analysis of hydraulic system wind generator

Wind power generation units of the hydraulic system is actually brake system drive, the main to execute the rev. Stop the wind generator task. Usually it consists of two pressure keep return composition: all the way through the accumulator is supply impeller brake system; All the way through the accumulator is supply yaw brake system. The two circuit task is when the wind generator during normal operation, make fan brake system always maintain the pressure. When pressure sensors to pressure value is less than the set value system, PLC will control hydraulic pressure station motor start to compensate for the loss of the pressure, the pressure value in the set value above always

Hydraulic system pressure of work is the actual change is always in the state of the reasons within the system, disclosure, the oil temperature change and electromagnetic valve movement and the oil problem. In theory the hydraulic elements not inside leaking, and actually components inside leaking can not be ignored. The higher the oil temperature the rare inside leaking oil, the more serious, the lower the pressure. The hydraulic oil pollution, it is to show from the outside with air, water and various curing content to wait, use of corrosion of metal powder such as mixing, and destroys sealing material, coating and broken substance. The oil contamination, will aggravate the hydraulic element relative motion between parts wear, cause throttling the hole of rotary motion picture card blocked or death hydraulic components can't work normally. Used in hydraulic system of compressibility is very small, in general, oil may think that oil is incompressible. But the air compressibility is very big, about ten thousand times the oil, so even if the system contains a small amount of air, its influence is also a lot of, dissolved in the air, in the low pressure oil will escape from the oil, have a bubble, form caities which act to high in the phenomenon, and under the action of pressure oil, these bubbles and soon breached, by compression, and makes the system sharply in produce noise, and at the same time in the gas by compression suddenly will give off a lot of heat, so as to cause local overheating, speed up the oil temperature is high, make hydraulic components and hydraulic oil were damaged. The air compressibility big, still can bring about working organs have fault creep, destroy the smoothness of the work.

Below will respectively to the yaw braking system and the impeller brake system is analyzed, and the fan operation hydraulic system driver.

A, the impeller brake system

Change propeller system is wind power conversion system's main brake system (the first and the second). It is designed to every blades have independent electric drive, and a battery to ensure the safety of the fault. There is a mechanical brake installed in the transmission chain high-speed side. This mechanical braking system is wind power converter system of the third braking system, but it is not designed to when the first and second brake system failed to keep wind energy conversion system in any conditions not more than speed limit allowed. Machinery brakes is the basic function of as the rotor system by change from the rotor slowdown to stop after it completely. Machinery brakes also used in the emergency stop when wind power conversion system slow down as soon as possible. This the mechanical brake drive mode is a hydraulic drive source for.

Hydraulic system of impeller brake system: normal operation, the brake open and close brake electromagnetic valve, release the brake rotor to electricity. Emergency cases, brake open and close brake electromagnetic valve lose electric, and accumulator pressure oil into the open valve brake the brake caliper, rotor braking. Pressure sensors in the brake oil chamber pressure below a certain value development (broken. Pressure sensor to monitor the accumulator ChongYa 2, when pressure value is less than the set, PLC control the oil pump motor start ChongYa.

Second, the yaw brake system

Yaw braking mechanism consists of 8 ~ 10 hydraulic control yaw brake discs to form. The system has two pressure, provide the damping yaw respectively and yaw end of braking. When the yaw when not working all brake brake locked; When the engineroom of wind all brake discs at half loosen state, set enough, keep smooth damping cabin yaw, at this time the yaw brakes used as a damper; Automatic solution cable, brake yaw released in full.

Hydraulic system yaw brake system: the yaw the electromagnetic valve, pressure to electricity, yaw brake release; Yaw half relief electromagnetic valve to electricity, 45 bar relief valve adjust the pressure when half brake; The throttle control brake up press time.

Three, when the fan operation hydraulic system driver

Hydraulic system in brake with ball valve, so that side of the screw in the piston hydraulic pressure for braking when can the wind generator. When boot instructions issued, brake open electromagnetic valve, brake calipers to electricity to the fuel tank, and brake so far and release. Suspended during the state of the operation to keep. When down instructions issued, brake open electromagnetic valve, losing electricity from the pressure of the pressure reducing valve accumulator and oil can be through the brake open electromagnetic valve into brake hydraulic cylinder, realize the braking when stop. When the emergency stop, brake open electromagnetic valve lose electric, and accumulator will pressure oil through the brake open electromagnetic valve into the brake caliper hydraulic cylinder. Brake hydraulic cylinder of speed by the throttle control. 

The concept of diesel generators and test methods

 Modern diesel generator set diesel engine, three-phase AC brushless synchronous generator, control box (screen), cooling water tank, coupling, fuel tank, muffler and other components of public base steel as a whole. The engine flywheel and the generator uses the front cover of the axial positioning of the direct connection convex form one shoulder, and the use of cylinder-type flexible coupling from the generator directly driven flywheel rotates its way connected together by a screw, so that the two are connected into a steel body, to ensure the engine's crankshaft and generator rotor concentricity within the specified range. 

  Diesel generators and synchronous generators by a combination of internal combustion engine, the engine maximum power by parts of mechanical load and thermal load limits, known as the rated power, AC synchronous generator rated power is the rated speed, long-term continuous operation, the output power rating, usually diesel engine rated power output of the alternator output and synchronization between the rated power, called matching ratio. 

1 Overview 

  Diesel generator set is a small power generation equipment, means the diesel fuel to diesel engines as prime mover drivengenerator to power machinery. General by the diesel engine diesel generator, generator, control box, fuel tank, starting with the storage battery and control, protection, emergency cabinet and other components. Can be fixed based on the overall positioning using, also mounted on a trailer for mobile use. 

  Diesel generator sets are non-continuous operation of power generation equipment, continuous operation if more than 12h, the output will be lower than the rated power of about 90%. 

  Although lower diesel generator power, but because of its small size, flexible, lightweight, fully furnished, easy to operate and maintain, it is widely used in mining, railways, field site, road maintenance, as well as factories, businesses, hospitals and other departments as a temporary backup power supply or power. In recent years, newly developed unmanned automatic emergency power plants, more kinds of generating units to expand the scope of use. 

  At present, China has a production capacity of export production plant in Tianjin more than 10 plants and other power equipment. Products are exported to Europe, Asia and dozens of countries and regions, well received. 

2 Classification and specifications 

  Diesel generator sets to the size of the generator output power to classify units of energy from 10kW-750kW variety of specifications. Each specification is divided into a protective type (with super-speed, high temperature, low oil pressure protection device), emergency-type and several structure-based mobile station. Which mobile station is divided into speed and vehicle speed can match the high-speed and low-speed off-road type of ordinary mobile type. 

3 Order Notes 

  Diesel generator set export inspection is based on contract or technical agreement on technical or economic indicators can be tested, the user in the selection and signing, should note the following: 

(1) If the environmental conditions and calibration of diesel generator sets the value of a gap when the environmental conditions should be described in the contract when the temperature, humidity and altitude values, in order to provide appropriate models and equipment; 

(2) Description taken in the cooling mode, in particular, large capacity units, should pay attention; 

(3) When ordering, in addition to illustrate the unit model, but also shows selection of the model; 

(4) diesel engine group voltage regulation rate of 1%, 2%, 2.5% of the rated voltage. Choose what should description; 

(5) normal delivery, provide a certain amount of wear parts, while necessary, should be described. 

4 test items and methods 

  Department of diesel generator sets of products, including diesel engines, generators, control components, protection devices. Exports of machine inspection, including the following: 

(1) product technology, test data review; 

(2) Product specifications, models, mainly structural dimensions; 

(3) the overall appearance of the product quality; 

(4) Unit Performance: The main indicators of technical parameters, plant operation flexibility, the reliability of automatic protection devices, sensitivity; 

(5) the contract or technical agreement of the other projects.

Diesel generator power distribution control section Troubleshooting

First, when the key to "START", the Diesel Generator Set does not start 
1, check the key switch operation is good 
2, check whether the fault indication, the repair and reset 
3, check the battery voltage of Generator Set, such as the voltage is too low, you need to recharge the battery to full, such as the voltage is normal, you need to step through the correct voltage signal was sent to all the control aspects, such as the throttle valve and start the motor, etc. 
4, check whether the emergency stop button of Generator Set is relax 
Second, when the "START" signal is entered correctly, but the manual / automatic will not turn on 
1, check whether the emergency stop button of Generator Set is relax 
2, check whether the control key "STOP" position 
3, check for fault indication, the repair and reset 
4, check the battery voltage of Generator Set, such as the voltage is too low, you need to recharge the battery to full, such as the voltage is normal, you need to check the signal was correctly sent to all control areas, such as the throttle valve and start the motor and so on. 
5, if all external electronic control part of the Generator Set no problem, you should replace the corresponding part of the electronic control 
Third, start the motor running, but the unit vain car 
1, check the fuel level, and to ensure that tubing is properly connected 
2, the mechanical speed control system unit of Generator Set, check the throttle valve is correct pull 
3, the electronic speed control system unit, check whether the correct access and EPG power voltage is normal 
4, the electronic speed control system unit, start the motor running, Measure the MPU have the correct AC voltage signal 
5, check whether the machine speed of Generator Set has reached or exceeded the normal speed setting of the start 
6, check the fuel delivery system is blocked 
7, check the air filter of Generator Set is clogged 
8, cold regions of the unit, before the start, make sure the unit warm-up 
Fourth, the high-temperature fault alarm / shutdown 
1, check whether the unit overload 
2, check the radiator of Generator Set is blocked 
3, check the fan belt tightness 
4, standby group completely cooled, check the adequacy of the cooling water level 
5, check the water temperature sensor of Generator Set is damaged Wei 
6, check whether the right to open the thermostat valve 
7, check the gap between the pump and the tank is correct 
8, confirm the room temperature of Generator Set is not higher than 40 °C 
Fifth, low oil pressure fault alarm / shutdown 
1, check the oil level of Generator Set
2, check the oil quality and viscosity 
3, check the oil temperature 
4, check the oil pressure sensor of Generator Set is damaged 
5, check whether the oil filter and oil quilt block 
Six speed downtime 
1, check whether the abnormal speed meter indication 
2, the mechanical speed control system of Generator Set, check the throttle lever is flexible, and ensure the correct adjustment 
3, the electronic speed control system of Generator Set, check the throttle lever is flexible, check whether the enforcement agencies the right action, and ensure the correct adjustment EPG 
4, re-calibration and adjust speed limits to protect 
5, troubleshooting, control panel will reset the alarm signal 
Seven, high voltage alarm 
1, measuring the actual value of the output voltage unit of Generator Set
2, and confirm that there is no deviation meter 
3, such as high voltage actual value, according to the steps detailed examination and re-adjust the AVR 
4, confirm the very nature of the load, power factor does not advance 
5, confirm the unit speed / frequency normal of Generator Set
6, such as the actual value of the normal voltage, check voltage display part of the circuit is correct 
Eight, low voltage alarm 
1, measuring the actual value of the output voltage unit of Generator Set
2, and confirm that there is no deviation meter 
3, such as the actual value of the voltage is low, according to the steps detailed examination and re-adjust the AVR 
4, confirm the unit speed / frequency normal of Generator Set
5, such as the actual value of the normal voltage, check voltage display part of the circuit is correct 
6, confirm that no major bias voltage three-phase 
7, confirmed that no phase phenomenon of Generator Set
8, confirm that when an alarm occurs, the load changed slightly 
9, confirm the operation unit is not overloaded of Generator Set
10, check the voltage high and low alarm settings are correct and reasonable limits