Look closely at the images posted by RoyB. The connector you have on the cord you show does not match the 3 pin connector in Roy's images, AS IT SHOULD. I'm thinking the cord/connector you have (without researching it) may be a 240 volt cable for an electric dryer. The correct connector will have 1 round pin and 2 flat ones in the V configuration. Don't use a power source of 240v for your 120v trailer, you'll burn up things in the trailer. This is just a quick word of caution and hopefully others have more info at the ready to help you.