Xantrex Technology 806-1055-02, 806-1840 manual Inverter Applications, Resistive Loads, Motor Loads

Freedom HF InvChg Owners Guide.book Page 42 Tuesday, April 29, 2014 12:10 PM

Inverter Applications

The Freedom HF performs differently depending on the AC loads connected to it. If you are having problems with any of your loads, read this section.

Resistive Loads

These are the loads that the inverter finds the simplest and most efficient to drive. Voltage and current are in phase (i.e. in step with one another). Resistive loads usually generate heat in order to accomplish their tasks. Toasters, coffee pots, and incandescent lights are typical resistive loads. It is usually impractical to run larger resistive loads—such as electric stoves and water heaters— from an inverter due to their high current requirements. Even though the inverter can most likely accommodate the load, the size of battery bank required would be impractical if the load is to be run for long periods.

Motor Loads

Induction motors (motors without brushes) require two to six times their running current on start up. The most demanding are those that start under load (e.g. compressors and pumps). Of the capacitor start motors (typical in drill presses, band saws, etc.), the largest you can expect to run is 1/2 to 1 hp (the transfer relays are rated at 2 hp).

Universal motors are generally easier to start. Since motor characteristics vary, only testing will determine whether a specific load can be started and how long it can be run.

If a motor fails to start within a few seconds or loses power after running for a time, it should be turned off. When the inverter attempts to start a load that is greater than it can handle, it will turn itself off after a few seconds.

Long Transfer Times

A specific situation has been observed where the Freedom HF may take a long time (~ 0.1–0.2 seconds) to transfer to inverter mode when shore power fails. This can occur when the Freedom HF is used to power motor loads where the motor is able to “freewheel” when power is removed (for example, a grinder). This long transfer may cause connected computers or other sensitive equipment to operate incorrectly. To avoid this effect, it is recommended not to connect motor loads together with sensitive equipment to the inverter for power.

42 Freedom HF Owner’s Guide