1) You are grilling fatty ingredients.
If you grill fatty ingredients like bacon or pork belly, you may notice some smoke coming off the food. Some of the fat will splash onto the sides of the grilling elements and burn. In this case, use the grill under the extraction hood.
2) You marinated your ingredients with a lot of oil.
The oil you use to marinate the food is burning and this causes some smoke to come off the food. In this case, use the grill under the extraction hood. To minimize smoke production, use no oil or only a little.
3) You are grilling several batches one after another and did not clean the grease tray and/or the grid after each batch.
Excess oil and food juices or food residues that remain on the grid and in the drip tray will start burning. Make sure you wipe the grid and drip tray with paper kitchen towels after grilling each batch.
Caution: the grid and drip tray are hot during and some time after use. Use oven mitts or pot holders when you handle these parts.