I am having a tough time finding a replacement transformer for my Hampton Bay 12V halogen track lighting(Home Depot). The halogen bulbs are 20W each and there are 7 of them on the track. The transformer is a Wang House unit rated at 230 watts, 12Volts and my understanding is I only need as many watts as there is for the total number of bulbs... ie, 7 bulbs x 20W each = 140 watts. Will a 150W rated transformer be suitable as a replacement part?