Transformer operation issues

An excessive starting current mainly affects power supply equipment and other electrical devices. When the transformer capacity is insufficient, the high starting current of the motor causes the supply voltage to **drop, affecting the proper operation of other motors and equipment. The impact on the transformer itself can lead to its direct destruction, causing a fire; in severe cases, it can even result in the explosion of the transformer, with consequences that are unimaginable. For a transformer, full load refers to the point at which the magnetic flux density in the transformer’s core reaches saturation. In this condition, as the current on the primary side of the transformer continues to increase (that is, as the load increases), the current on the secondary side does not increase accordingly. The additional current on the primary side is then entirely converted into copper losses, which can lead to the destruction of the primary winding! Why does a transformer operate at full load? This is because, regardless of the material of the core, as long as its dimensions remain fixed, the maximum magnetic density it can achieve is also fixed; once this magnetic density is reached, the core becomes saturated! It’s like a box – it will always be full at some point! For reference, please see Clause 4.2 of the \"DL_T_572-2010 Operating Regulations for Power Transformers\".

This is clearly unreasonable – the operating current alone for the cooling unit and one circulation water pump is 650 + 82 = 732 A, which is already greater than the transformer’s rated current of 721 A, not to mention during startup! The transformer chosen is too small.

We have already started using it. I need to write a letter to my supervisor, and I will need some documentation to support it. Do you have any such materials?

1. Increased losses in the transformer: Since transformers are designed for a certain rated capacity, their optimal operating point is around 67%; when the load on the transformer exceeds this rated capacity, its copper losses increase in a quadratic manner； 2. Decreased transformer output voltage: When the load exceeds the transformer’s rated capacity, the secondary output voltage of the transformer will drop; when the output current reaches the short-circuit current level, the voltage drops to zero ； 3. Reduced lifespan of the transformer: The windings of oil-immersed transformers are typically made of Class A insulation materials, which have a heat resistance temperature of around 105 degrees. Exceeding this temperature accelerates the aging of the insulation material, and prolonged operation under overload conditions can cause the transformer to overheat or even burn out. 4. I really don’t know how you guys inspect these transformers

This post was last edited by Deep blue, azure on 2019-6-6 at 16:23. Overloading a transformer refers to operating it at currents that exceed those specified on its nameplate. When a transformer operates under severe overload for an extended period, it not only results in a reduced output, but also increases losses; furthermore, it can lead to damage to the transformer equipment, which is detrimental to its safe and economical operation. I. Overloading reduces the efficiency of transformers. The losses in a transformer arise mainly from iron losses and copper losses within the transformer. According to the transformer efficiency curve, when the output of the transformer is zero, its efficiency is also zero ； As the transformer output increases, efficiency starts to rise until it reaches a maximum, after which it begins to decline again. This is because the iron loss of a transformer remains essentially constant regardless of the load, resulting in low efficiency at light loads. Copper loss, on the other hand, is proportional to the square of the load current; as the load increases, copper loss rises rapidly, which in turn reduces the efficiency of the transformer. It can therefore be seen that operating a transformer beyond its capacity does not result in it handling more load or producing more power – rather, it has the opposite effect, reducing the transformer’s efficiency in terms of power output. Of course, it is also possible to operate the transformer under overload, but there are conditions for this. The overload capacity of a transformer is determined by its capacity; it can handle loads higher than its rated load, but not beyond the specified load multiplier and allowable overload duration, and the temperature rise of the transformer must not exceed the prescribed limits. According to relevant information, the lighter the overload, the longer allowable duration cannot exceed 30 minutes either when it is 1.3 times the limit. II. Impact of Overload Operating Temperature on the Transformer The temperature rise of a transformer has a significant effect on its operation, primarily affecting the insulation strength of the transformer. As the temperature of the transformer rises, the resistance of the windings increases, which in turn leads to higher copper losses. Additionally, the temperature rise in the transformer affects the strength of the insulating materials as well. During production, transformers use two main types of materials: an iron core made of metallic material, and high- and low-voltage coils made of insulating materials. The transformer core can withstand high temperatures without being damaged, but once the temperature of the windings exceeds a certain level, significant damage will occur. Especially during the height of summer, when the ambient temperature can reach 40 degrees Celsius, operating a transformer under overload conditions can cause its temperature to rise to 100 degrees Celsius or more. If it continues to operate in such conditions for an extended period, the insulating materials within the transformer will gradually lose their original mechanical properties. The higher the temperature, the faster the insulation deteriorates; without the protective layer of insulation around the coils, the transformer can even be damaged beyond repair. Suggestions: 1. When the transformer is operating under load, the maximum load should preferably not exceed the transformer’s rated capacity; this ensures that the transformer operates under normal conditions, the insulation of its windings deteriorates at a normal rate, and thus the transformer’s service life can be extended. 2. If the transformer operates under overload conditions, it is necessary to strictly adhere to the permitted degree of overload and the allowed duration of such overload, as well as to ensure that the temperature does not exceed the specified limits for the transformer, in order to prevent damage to the transformer. 3. When configuring transformers, it is necessary to consider those with the highest efficiency, and sufficient headroom should be left to meet the user’s needs under maximum load conditions. This ensures maximum output from the transformer, minimum losses, as well as improved power supply quality and reliability. According to the basic theories of Electrical Engineering, ； The maximum efficiency of a transformer is generally achieved when the load on the system is between 0.5 and 0.6. The load on the transformer should not cause it to operate constantly at full load or light load; an efficiency level of around 0.7 is appropriate. It is necessary to leave some headroom in the transformer’s capacity to meet the requirements when it is under its maximum load. 4. For transformers that have a small capacity and are severely overloaded, measures such as load sharing or installing an additional transformer should be taken to address the issue. The capacity of the additional transformer should be determined based on the power supply area and the load conditions.

The transformer capacity is too small; the starting current of the chiller is too high, resulting in a large voltage drop and an increase in current, which in turn creates a short-circuit current

Is this ice machine low-pressure? ? ? ? ? ? ? ? Hey, doesn’t the 2000A starting current require a soft start? The load current seems fine; dry-type transformers have a greater overload capacity. As long as the operating temperature doesn’t exceed 80 degrees, there’s no problem.

The current value can be calculated with the help of a capacitor. Check the starting current to see if overload is likely to occur.

I don’t understand this area; I’ll learn it*:D