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Influence, Causes and Solutions of the Temperature of the Generator Set

Sep 18, 2023 | Operation and Maintenance | 0 comments

Abstract: Temperature is an important factor that affects the normal operation of diesel generator sets. It mainly includes ambient temperature (temperature) and the high temperature generated when the equipment is working. All diesel generators have a normal operating temperature range. According to the national standard GB/T2819-95, the best working environment for diesel generator sets is an absolute atmospheric pressure of 100KPa, an ambient temperature of 25C, and a relative air humidity of 50%. In this environment, Its working condition is optimal. If it is significantly lower or higher than this range, it will affect its output power and even lead to failure to work normally or damage. Since high and low temperatures are important factors affecting the normal operation of diesel generators, this article Guoda mainly analyzed the impact of the diesel generator set on itself due to the ambient temperature and the high temperature generated during operation, and focused on analyzing the reasons and proposing targeted countermeasures.

1. The impact of high temperature on the engine
The diesel generator set is mainly composed of three parts: a diesel engine, a synchronous alternator and a control system. The diesel engine is the commonly heard diesel engine. It generates power through the combustion of diesel, and then generates electrical energy through a coaxially installed synchronous alternator. This electric energy is then controlled by the generator exciter system to control the electric current, adjust and output the current to the power supply. Therefore, we first look at the impact of high temperature on its main engine (i.e. the engine), the causes and solutions.

1. Impact
The normal operating temperature of the diesel engine is 80C~95. When the temperature is significantly higher than 95C, it is a high temperature. The engine power will decrease, which will also cause the generator power to decrease and affect the power supply quality. A common redness in the supercharger and exhaust manifold is Typical phenomena of high temperature are shown in Figures 1 and 2. Secondly, the oil viscosity peak is low, which accelerates the wear of mechanical parts, and in serious cases can cause engine failure. “Opening the pot”, burning tiles, pulling and other old stories. Diesel generators also have a common problem. Because they are stationary when working, their front heating effect is poorer than that of cars. Therefore, when they work for a long time, they are often at a higher temperature without overheating. In the “boiling” state, operators often ignore this problem. In addition to causing a decrease in power, it often causes the cylinder gasket to leak, causing the generator set to be unable to work and require maintenance.

2. Causes
(1) Most of the causes of high temperature in diesel engines are caused by untimely maintenance, such as lack of antifreeze and lubricating oil, dirty radiators, loose fan belts, or aging of antifreeze and lubricating oil.
(2) Diesel engine parts, such as mechanical failures in thermostats, cooling fans, water pumps, etc.
(3) The phenomenon of high temperature is caused by excessive engine load or low oil pressure in the fuel supply system, poor atomization, and insufficient combustion.
(4) Due to the operator’s fault, the engine is not working properly or there are safety hazards, and the operator fails to eliminate them in time, or operates in violation of regulations.

3. Countermeasures
(1) Before starting, the quantity and quality of engine oil and anti-fouling fluid should be checked. If they do not meet the requirements, they should be supplemented or replaced. At the same time, the connection of each component of the engine should be checked, whether the circuit contact is firm and reliable, and whether there is any open circuit; oil Check whether the road is clogged or leaking, and whether the transmission belt is aging, loose or slipping.
(2) Maintain timely and strictly in accordance with regulations. The maintenance process is also an inspection process. Hidden dangers should be eliminated promptly to keep the equipment in good condition. Operators should usually strengthen their professional theoretical study and education in thoughts, responsibilities, etc. to improve their business capabilities. .
(3) If the machine or parts are found to be faulty, they should be replaced in time, and the load should be adjusted in time if the load is too high.
(4) In view of the high temperature that often occurs in generator sets due to heat dissipation problems, the following methods can be used: 0 If it is an outdoor container generator set, it can be used alternately with one standby and one in use if conditions permit, or a generator set with a higher power level can be selected. , an unstructured method that can reduce part of the electrical load, and can also be used before purchasing
The supplier is required to assemble electric louver fans to solve the heat dissipation problem, as shown in Figure 3. 0 If it is an indoor fixed generator set, the method of building a hot water pool + cooling water tower combination can be used to replace the heater and wind bottom. The installation process is shown in Figure 45, and a Xinhuan cooling water pool is built in the machine room. The anti-dong liquid is placed in the pool, and when the water enters the system at t0, it heats the engine through the external signal ring of the water tower: its advantage is that the front heating effect is good. Reduce the size of the generator set, reduce the peak noise, and increase the output power. This method can be used in outdoor situations where there is no mains power, the construction period is long, and the power supply is large, or for marine generator sets.

2. The impact of high temperature on generators
1. Impact
Generators of different types and functions have different temperature requirements. According to the standard GJB235A-97, the operating temperature of generator bearings should not be higher than 80%C~90C, and the limit temperature of braiding materials should be between 90C~180C. (The limit temperature of 180C is a Tezhu generator). That is to say, when the generator is working, the lower its temperature is, the higher its efficiency will be. The empirical method to judge the temperature of the generator is that it is not hot to the touch (a temperature tester can be used for safety reasons), which is about below 50 “C. If If it is close to the limit value of the insulating material or higher than this temperature, the temperature of the generator will be too high. If the temperature of the generator is too high, it will affect its output power and shorten its service life. In severe cases, it will cause short circuit between windings or between coils and damage the generator. 

2. Causes and countermeasures
(1) The load is too large and the startup is too frequent.
Measures: Adjust in time.
(2) The three phases are unbalanced or missing. The phase sequence may be artificially connected or the winding insulator may be aging.
Measures: Check and adjust in time. If the overall insulation of the winding is aged, it must be re-winded and overhauled.
(3) The bearings are worn, causing the rotor and fixed shaft to become damaged.
Measures: The bearings should be replaced with new ones and the condition of the winding should be checked. If damaged, it needs to be re-winded and overhauled.

Influence, Causes and Solutions of the Temperature of the Generator Set
(4) Output voltage higher than 10% of the rated voltage or lower than 5% of the rated voltage will also cause high temperature.
1. Adjust the transformer switch position to the normal range.
2. If the diesel engine speed is too high or too low, it should be adjusted to the normal range.
3. The generator stator and excitation winding are short-circuited or grounded, and the brush contact is poor. It should be checked, eliminated and adjusted by polishing.
(5) The ambient temperature is too high or the heat dissipation performance of the generator is reduced.
Measures should be taken to maintain indoor ventilation, check whether the cooling fan is damaged or slipping, and whether the water pipe is blocked. If found, it should be eliminated in time.

3. The impact of low temperature on diesel generators
1. Impact
The influence of low temperature mainly refers to the ambient temperature. Winter temperatures in northeastern and northwest my country are mostly below 20°C, and extreme temperatures can reach -30~40°C, which has a great impact on the use of generator sets. (1) The generator operates at low temperature. Working in this environment will theoretically reduce the output power, but heat will be generated during operation and needs to be removed. Therefore, when the generator works to normal temperature, the impact of low temperature can be ignored. (2) The biggest problem with the impact of low temperature on the generator set is the startup of the diesel engine, which cannot reach the optimal working condition at startup. A period of time after starting, causing the power to drop.

2. Causes
(1) In low temperature environments, the viscosity of lubricating oil increases, which increases the movement resistance of various components in the body.
(2) The battery power is reduced, resulting in insufficient power to start the engine. Since the optimal operating temperature of the battery is between 10C and 20C, when the ambient temperature is lower than -20C, its rated output is less than 50%, so the battery capacity of the battery will be significantly reduced.
(3) The viscosity and density of diesel increase: According to measurements, when the temperature is from 30°C to -10°C, the viscosity of diesel increases by about 80% and the density increases by 8%, resulting in poor fluidity and poor meltability. , in severe cases, it will cause the diesel to condense and wax, making it impossible to start.

3. Countermeasures
(1) Use lubricants with better low-temperature performance and low-temperature special batteries
(2) The freezing point of the selected antifreeze should be at least 5°C lower than the ambient temperature.
(3) Increase the ambient temperature of the machine room and insulate the generator set, especially the battery, on site.
(4) Strictly follow the correct startup procedures. When starting at low temperature, preheating should be performed first (mainly including fuel heater preheating, flame preheating and resistance wire preheating). Each start should not take more than 10 seconds, and 3 consecutive starts should fail. There should be a pause of 2 to 3 minutes afterwards. If it still doesn’t start, you should check. In extreme racing weather, methods such as rolling over, using low-temperature starting fluid, and artificial heating can be used. Note: When heating the oil pan manually, do not use an open flame to heat the oil pan. This can easily damage rubber and plastic pipe fittings or cause fire. The safe thing to do is to drain the antifouling fluid and add warm water to the tank while it is emptying. When the outflowing water is also warm water, add water with a higher temperature, such as 80%C~90C water. After the engine is started, the water should be drained out in time to prevent condensation: when starting the engine at low temperature, the intake flame is not preheated. Using them simultaneously may cause an explosion.
This article mainly analyzes the impact of temperature on diesel generator sets and their causes, and proposes countermeasures: However, there are many factors that affect the normal operation of diesel generator sets, such as the professional level of the operator, the age of the operator, etc. The equipment itself, as well as other environmental factors such as wind, sand, rain, snow, lightning, etc., all require maintenance, management and use personnel to understand and learn.

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