Load conditions and cooling protection devices for explosion-proof electrical equipment - News - Global IC Trade Starts Here Free Products

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

1.5PF SOT23-6 Low Capacitance 5V Breakdown Voltage 6V SRV05

Shunuo varistor / ESD varistor / product complete / Sunlord first-class agent

If the various conditions that affect the temperature rise of the explosion-proof electrical equipment are not appropriate, it may cause danger. Therefore, when selecting explosion-proof electrical equipment, these conditions must be carefully studied.
1. Load condition
(1) Working mode and rated value The rated value of explosion-proof electrical equipment must be suitable for the load value under the working mode of the equipment. The relationship between working mode and rating is as follows:
A. For continuous operation, continuous rating should be used;
B. For short-term work, short-term ratings should be used;
C. Intermittent working mode, repeated working mode, should adopt the continuous rated value, short-time rating and repeated rating of the heat and cooling state of the explosion-proof electrical equipment in the corresponding operation.
(2) Working characteristics Explosion-proof electrical equipment must be selected according to the conditions of use to select the appropriate operating characteristics.
A. Explosion-proof electrical equipment should study the moment of inertia, braking type and braking time of the specified load, as well as the load duration and frequency, in the case of repeated starting, stopping or turning.
B. When it is necessary to control the speed, the speed control range and load characteristics (constant torque or power, etc.) are specified.
The various working methods mentioned above are explained as follows:
Working time refers to the state of use of explosion-proof electrical equipment during load time.
The continuous working mode actually means that under a certain load, after the temperature rise reaches the specified value, it continues to operate.
The short-time working mode means that under certain load, the explosion-proof electrical equipment should be stopped within the range where the temperature rise has not reached the maximum specified value. After the specified time has elapsed, it should be stopped. When the temperature of the equipment drops to the same level as the ambient temperature, it should be restarted. .
Intermittent working mode means that under certain load, the explosion-proof electrical equipment will reach the highest specified value within the temperature rise, and after a certain period of time, it will stop. If it does not fall to the same temperature as the ambient temperature, it can be used again. Running under the same load, you can work repeatedly at irregular intervals. The repeated work mode refers to the running period and the stop period as a cycle, which is a repeated work mode.
2. Cooling method and its protection device Explosion-proof electrical equipment achieves the purpose of lowering the temperature by cooling, so the cooling method and cooling conditions should be determined. Explosion-proof electrical equipment cooling methods are generally divided into self-cooling and cold cooling. Self-cooling relies on the conditions of the explosion-proof electrical equipment itself to dissipate the heat generated by itself. Some devices have fins on the surface of the casing, and heat is dissipated through the fins; some add a cooling fan to the rotating shaft, and the heat is taken away by the fan. He is not relying on the own conditions of explosion-proof electrical equipment, but instead adds a fan to cool the explosion-proof electrical equipment. Such motors, transformers, high and low voltage switches have adopted this cold form cooling method. In addition, there are water cooling inside the enclosure or explosion-proof electrical equipment. The above cooling method is of great significance for the cooling inside the explosion-proof electrical equipment and the ignition of the explosive mixture. Generally, in order to prevent the malfunction of the ventilation device or the interruption and reduction of the cooling water, a signal and an alarm device can be immediately installed on the device, and when a dangerous state occurs, the power can be immediately cut off and the device can be stopped.