Good day. Can you switch on an inverter without any other connections like a inverter out, solar and battery connections to see if it's working and the settings. 

Only inverter in connected to a 3 pin plug and switched on. 

Thank you

Welcome to the forum.

Depending on your inverter, it would be best to startup on battery, and if all is setup and working correctly, switch on mains AC and Solar.

If you are running a grid tied inverter this is not necessary, and working off mains AC is expected.

A current limited power supply is best, but note that if the power switch is on, it will try to start the DC-AC converter, which will likely be too high a power surge for a typical bench power supply.

You  can use a set of 12 V batteries, but use inrush protection to prevent a massive current spike and splat. This is not good for the wiring, connectors, capacitors, and even your eyes.