All modern day travel trailers use a combination of 12 volt and 110 volt electrical components. If you stay at a campground that has hookups they will offer 30 and or 50 amp service. The 50 amp service is necessary when your trailer needs to run two roof airs, microwave and maybe the refrigerator.
Your 12 volt system in your trailer is responsible for running the lights, vent fans, part of your refrigerator when on gas, and water pump. Your electrical appliances like the microwave, roof airs, electric water heater and coffee maker will use the standard 110 volts like in our home.
Your travel trailer will be equipped with a circuit breaker panel that will look similar to the one in your house. Sometimes the breakers will be push button instead of your standard breaker switch but they operate the same.
When your 12 volt system displays problems it usually means the trailers transformer is malfunctioning. The transformer is responsible for converting the 110 volt to 12 volts. If you need to replace the transformer it can be very expensive. The 12 volt system will have a fuse panel that will protect your 12 volt accessories. It is important to check these fuses to make sure one has not blown. This would cause that one particular item not to work if you have a blown fuse.
If you have an analog or digital multi-meter available this can be a great help in finding and fixing 12 volt and 120 volt electrical problems. Just by using the basic functions on the multi-meter can help track down electrical problems.