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How To Calculate Cable Load

Cable Load Calculation Methods

At present, the demand coefficient method and the binomial coefficient method are widely used in China to determine a load of electrical equipment, among which the demand coefficient method is the most simple and widely used in the world to determine the calculation load.

The binomial coefficient method is more reasonable to calculate the load of the branch trunk with a few types of equipment and different capacity of each equipment.

In building power distribution, the load density method and the unit index method are also commonly used to calculate the load. The unit index method can be used in the stage of scheme design. In the preliminary design and construction drawing design stage, it is appropriate to adopt the need coefficient method.

Load Calculation Principle

When calculating the load the equipment power should be calculated according to the following principles.

cable current load

The related power of electrical equipment with different working systems should be converted into a unified equipment power.

The equipment power of the rectifier refers to the rated AC input power.

The equipment power of a group of electrical equipment shall not include spare equipment.

When the calculated active power of firepower is greater than that of firepower, the general power and lighting load may be removed at the same time to calculate the active power. The total power of low-voltage equipment should be calculated according to the uncut general power and lighting load plus the fire load.

Otherwise, the fire-fighting load should not be considered when calculating the total low-voltage load. When there is a load in the fire-fighting load and peacetime use, the part of the load should also be included in the general power and lighting load.

The single-phase load shall be evenly distributed to the three-phase load. When the total calculation capacity of the single-phase load is less than 15% of the total calculation capacity of the three-phase symmetric load within the calculation range, all the three-phase symmetric load shall be calculated. 

When more than 15%, the single-phase load should be converted to the equivalent three-phase load, and then added to the three-phase load.