Introduce Yourself

I'm new here and have been building a layout in my garage over the past few years and also with the intention of going into the garden too. I recently purchased Mallard LS online but require your help and advice on starting out. When I switch on the controller and turn the dial to super heat the voltmeter reads 17 volts but after a few seconds a short circuit occurs and an audible warning sounds. I've tried several times and every time it does this. Any suggestions?