Dehydrator is a very poor food warmer. It dries, warms and cools the food at the sametime. (Latent heat lost from evaporation).
Use your microwave, cover the food and set the power at 1 or 2or 3, depending on your MW's power.
For warming plates: Put a wet thin napkin in between every two plates and MW. You can stack as many plates as your MW can take. You can get all the plates boiling hot in no time.
dcarch