Yes, DYNAMOS is a Scrabble word!

Letter values in Scrabble US: D 2, Y 4, N 1, A 1, M 3, O 1, S 1.

Is it a valid word?

DYNAMOS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

generator consisting of a coil (the armature) that rotates between the poles of an electromagnet (the field magnet) causing a current to flow in the armature