Generator IP, Insulation, Temperature Rising Levels
:Ingress Protection (IP Level):
Protection grade level of generator is usually adopted for IP21, IP23, IP44, IP54.
Protection grade level of Stanford generator is IP23
Protection grade level of Marathon and Meccalte generator is IP21, and IP23 selectable.
Protection grade level of Leroysomer is IP23.
IP44, IP54, generally for the oilfield and the drilling platforms, by water or oil cooling generators.
Insulation Class:
Insulation class is the allowable working temperature of insulation structure. At this temperature
it can maintain its performance in a predetermined period. In the permitted range, it is divided into
several levels which are called temperature classification. According to the temperature classification,
heat resisting materials are divided into seven classes. They are grade Y 90℃, grade A 105℃,
grade E 120℃, grade B 130℃, grade F 155℃, grade H 180℃ and grade C 180℃. Beyond the limit,
the life of the insulating material will be dramatically shorten, even burned up. This temperature is called
allowable temperature of the insulating material.
Limit working temperature of the insulating material, refers to the generator runs in the hottest spot
temperature of winding insulation within its design life expectancy. As a matter of experience, the life of grade
A material can reach to 10 years at 105℃, the same to grade B material at 130℃. But in the actual cases, the
environment temperature and the temperature rise are not always at the design value for a long time. Therefore,
in general its life is between 15 to 20 years. If the operating temperature is always higher than its limit working
temperature for a long time, insulation materials will be serious aging, and its service life will be shorten.
Therefore the temperature is one of the main factors that affect the service life of generator when it is operated.
The most commonly used insulation classes of generator are A, E, B, F and H.
Temperature Rise Level
Temperature rise is temperature difference between the generator and the environment. It is caused by the
electric heating. Running generator iron core will produce iron losses in alternating magnetic field. After winding
current power on, Running generator iron core will produce copper loss and other stray loss, etc. These all will
make the motor temperature rise. On the other hand, the generator is also heat dissipation. When heating and
cooling are equal to equilibrium state, temperature will no longer rise and stay on a level. When the temperature
of the generator rises or its heat dissipation reduces, the heat balance will be destroyed. The temperature continues
to rise, and then temperature difference is increased. If increasing the temperature, the generator will reach a new
equilibrium in another higher temperature. However, the temperature difference or temperature rise has increased
than before. Therefore, temperature is an important index in generator design and operation. It shows the fever level
of the generator. If the generator temperature rise suddenly increases in operation, it shows the generator has a fault,
or the air duct obstruction or its load is too heavy.
Temperature Rise Level is generally based on the added value of the ambient temperature. For example, if level H
temperature rise is 125 ° C under environmental temperature 40 ° C, generator allows the highest temperature should not
exceed 165 ° C. If level F is the requirement of 105 ° C, generator temperature cannot exceed 145 ° C. So the same
type of generator with different Temperature Rise Levels, their power outputs are different. The higher Temperature Rise
Level leads to the greater power output. However, its life will be short. Generally, Temperature Rise Level F or Level B is
suitable for power plant and high voltage generator. Temperature Rise Level B is suitable for marine and oil field.
Generally, generator has no normal power and standby power. Its power is calibrated based on the Temperature Rise Level
under the ambient temperature. The normal power commonly referred of our generator is calibrated based on 40 ° C temperature
and 125 ° C Level H temperature rise. For the standby power of generator commonly referred, the accurate description
is that its standby power is calibrated based on the environmental temperature of 27 ° C and Temperature Rise Level H.
The significance of this calibration is that under the same allowable temperature of 165 ° C, if the environment temperature is low,
the allowed temperature rise range of the generator will be increased. Under the environmental temperature of 27 ° C, the allowed
temperature rise of the generator is 138 ° C.
The most commonly used Temperature Rise Level of generator are Level B, Level F and Level H.
Temperature Rise Level B is 90 ° C
Temperature Rise Level F is 105 ° C
Temperature Rise Level H is 125 ° C
Take Meccalte generator for example, generator type ECO43-VL/4, its output power is 1120kW in Temperature
Rise Level H and 1024kW in Temperature Rise Level F.
Stanford generator type HCI544F, in 40 ° C environment temperature, its output power is 536kW in Temperature
Rise Level H and 496kW in Temperature Rise Level F.
Marine generator type HCM534F in 40 ° C environment temperature, its output power is 404kW in
Temperature Rise Level F and 352kW in Temperature Rise Level B.
