Did you check to see if you have a timer set? The way you're describing it makes it seem like it has a bad safety circuit. Which means when the circuit senses overheating or possible danger to the components it'll turn it off. Also maybe the power supply is failing. It sounds like you might of possibly received a defected TV.
Check your warranty or contact their customer service for support regarding, the issue.
http://westinghouseelectronics.com/support/service/
Provide them with the model number
which is usually located by the power cord on the back of the tv.
Edited by Adroit, 2016-12-09 05:22:37