Durst TRA 305N - 2 output voltages

So

I was wondering... What if my power supply fails? What other option could I take.. So I was looking at my transfo and it has two output voltages, for one single bulb?

11V - 86VA
12V - 100VA

What is the reason for that? I have a Durst M305Cls (dichroic head).

Do you have a picture or schematic of this?

So. Instead of finding a schematic I ripped apart my enlarger.. Was just for a simple led. The bulb works on 12V.