DC injection brakes provide cost-effective way for both new and existing woodworking machines to comply with PUWER 98 safety legislation (04-Nov-02)
Entrelec MTE, a member of the ABB Group, has updated its Powerbrake range of DC injection brakes to incorporate a number of important new features such as thyristor integrity checking, increased braking time and automatic tripping should the time potentiometer fail.
Under the new PUWER (Provision of Use of Work Equipment Regulation 98) legislation all new woodworking equipment must already be equipped with an automatic brake that stops the tool in a sufficiently short time. From December 2003/ December 2005 (depending on the exact type of equipment) this standard will be extended to include second hand and existing machinery already in use.
The Powerbrake has been developed to provide a way of meeting the PUWER 98 requirement which is much more reliable than a mechanical brake and around one tenth of the cost of installing a braked motor. It is a solid state injection brake which provides frictionless, fast, smooth braking of single and three phase AC induction motors by injecting a controlled DC current into the motor windings; this introduces a stationary magnetic field which exerts a braking torque on the rotor.