This neat guide is from the Trudeau Corporation in the USA who make and supply Raclette Grills there. We do not sell their grills - I don't believe that they are imported into the UK yet - but the brief guideline below is useful:

Raclette Trays

In another era, Swiss raclette was a very simple meal. Half a cheese round was heated in front of an open fireplace and the melting cheese was scraped onto potatoes, layer by layer. However, that old world method is a bit impractical for most modern households. Today, many retailers offer a variety of electric raclette machines in different models and price ranges. Any of the raclette machines you may purchase the principle is always the same. The ingredients are placed in small, non-stick raclette dishes to cook under a heating element.

Raclette Grill

The raclette machines most frequently sold today have a non-stick grill above the heating element and trays. This lets you grill meat, fish, or vegetables on top while the cheese melts in the trays below. Many of the recipes in Trudeau's book were developed for this type of appliance, allowing more variety in the type of meals you can prepare.

Raclette with Hot Stone

Grilling is an ancient technique that as a cooking method is low-fat and wonderfully aromatic, especially when you can cook your meal right at the table. The hot stone is pre-heated on the raclette machine's heating element. The heating element maintains a constant temperature and can be adjusted higher or lower by a control.