Sherwood Electromotion Inc. (SEI) supplies new coils, coil sets, and winding kits for various types of electrical rotating machines. SEI provides remanufacturing services for specific types of coils (eg. field coils) and offers complete winding replacement services (rewinds) for all types of electrical rotating machines.

Electric coils are parts of the winding systems in electrical rotating machines. These windings generate magnetic fields and also interact with magnetic fields to produce required output from electrical rotating machines. DC machines utilize field coils and armature coils, while AC machines have stator winding and rotor winding. There are two general types of electric coils: form-wound and random-wound, and their application depends on the type and size of electrical rotating machine.

In most cases electric coils are supplied as a coil set, which contains all coils required to wind a particular component of the machine, or as a winding kit, which in addition to the coil set contains requisite insulating materials and appropriate interconnection parts.