Load Types

What loads to look out for when sizing your inverters.

Electrical Inductive Loads

Inductive Loads

Inductive loads are mainly electric motors that require an electromagnetic field or “flux” in order to perform their function. These types of electronics perform work through making use of the induced magnetic field. In the case of an electric motor, the electric motor spins the drive shaft by use of repelling electro magnets. Capacitors and resistive loads also cause the same effect, using more power than they actually deliver.


Start-up Current

The “Start-up” current or Power-draw on an inductive load is dramatically more than it uses to run. This is due to the electro magnets having to fill with energy, having to start moving a stationary load as well as the motor is not very efficient in that state. Start-up current on an inductive motor can measure 6-10 times what it would use under normal running load, this is a big factor to take into account when choosing the correct size inverter for the application as the inverter will need to be sized for the start-up current, not only the running current of the loads.

Example: A 1.1Kw swimming pool pump will perform its daily function at 230Vac (Voltage-AC) with an amperage of 4.8A (Ampere). Within the first second or two of start-up, this same motor will draw around 28.7A (6.6Kw) depending on the start-up conditions (Temperature, Start-angle, Load, ETC).


Required Wave Form

Inductive loads require a pure or true sine wave to perform their function correctly. If an electrical motor is powered by a square or modified-wave, they will simply heat up and burn out. Bearing in mind that electricity and heat are both forms of "Energy", if the correct type of sine-wave is not delivered when and where the electrical motor needs it, the excess or lack of power in the right place and time will be turned to heat as it cannot be absorbed by the motors need to do the work. Most good inverters can handle around 2x their specified power rating for 5 seconds to allow for these kinds of loads.