Encoder Basics #1 11/8/2018

Encoder Basics We will be covering: Common names & definitions Types Technology Mechanical designs Output Applications Confidential

Different Names for Encoders Rotopulser Pulse Generator Digital Tachometer Tach Pulse Tach Shaft Encoder A lot of names….. Confidential

Definitions Tachometer – Analog device that produces a voltage proportional to speed. Encoder – Digital device that produces pulses based on rotational position Confidential

Encoder Basics Encoder Types: Incremental Provides identical electronic pulses at each division of shaft rotation. Used for speed or velocity control of motors Absolute Provides a unique electronic piece of information at each division of shaft position. Used for positioning systems Resolver Provides sine wave and cosine wave to provide both velocity and position feedback. Confidential

Encoder Basics Sensing Technologies: Magnetic (Magneto-resistive) Tough and simple Heavy Duty enough for Mills No Optics (no glass breakage) Limited to 2048 PPR Optical Higher Resolution (up to 10,000 PPR) Better signal quality Shafted and Hollow shaft designs NORTHSTAR DYNAPAR & NORTHSTAR HD OPTICAL Confidential

Magneto-Resistive Technology Features a magnetic pulse wheel that is imprinted with numerous, small magnetic poles. Rotation of the magnetic pulse wheel creates an alternating pattern of north-south magnetic fields for the pick-up head. The electrical circuit in the sensor produces digital pulses proportional to motor speed. Confidential

Optical Technology Utilizes a glass, plastic or metal rotating disc that operates in an light path between a photoelectric transmitter (LED) and receiver. Confidential

Encoder Mounting Styles 11/8/2018

Encoder Basics Mechanical Designs: Hollow Shaft Encoder mounting on shaft extension with bearings and torque arm. Coupled Machined face, bracket, stub shaft and a flexible coupling. Bearingless Frame of encoder bolts to motor, pulse wheel mounts on shaft extension or stub shaft. NorthStar: HSD35, HSD37, Slim Tach HS56 Dynapar: HS20 & HS35 NorthStar: RIM 6200, HSD44 Dynapar: H56 Rotopulser NorthStar: SLIM Tach: SL56, SL85, RL67 RIM Tach: RIM8500, RIM1250 Confidential

Hollow Shaft Encoders The lowest cost encoder to install No couplings to align or isolate No adapter (flower pot) No machined fan cover required on TEFC motors Flexible torque arm Allow encoder to ride freely on shaft extension If too rigid, provide stress on encoder bearings Arm must be isolated from motor to avoid motor shaft currents from damaging encoder bearings Ideal for Reliance TEFC V*S Master motors Good for all motor enclosures Confidential

Coupled Encoders Highest installation cost. Requires a expensive, flexible coupling Requires adapter (flower pot) between encoder and motor On larger motors, an expensive insulated coupling may be required to protect Coupled Encoder bearings V*S Master TEFC motors requires a special cast iron machined fan cover Flexible Coupling Machined Adapter Bracket Confidential

Bearingless Encoders Less space required No couplings to align or isolate Can have a thru shaft Can be mounted between brake and motor Can be mounted on drive or non-drive end No bearings to fail! Pulse wheel mounted directly on shaft extension Encoder housing bolted to motor bracket No concerns with motor currents damaging bearings Ideal for Reliance RPM-AC and DC motors Good to mount between brake and motor bracket on TENV, DPFV and TEBC-PB enclosures Not recommended for V*S Master motors Confidential

Incremental Outputs Magnetic & Optical 11/8/2018

Encoder Outputs Incremental encoders are usually supplied with two channels (A & B) that are offset by 90 degrees. If complements are included (A, B ), the signal is “quadrature”, providing speed of rotation AND direction of rotation. Confidential

Single Output, Quadrature Signal with Complements Signal A leads B in one direction, B leads A in the reverse direction Complement pulses, A and B are used to provide electrical noise immunity for the signal as it travels through the cable. Confidential

Marker Pulse A marker pulse (reference, index or Z pulse) is a once per revolution pulse that occurs at precisely the same mechanical point in a 360º revolution of the encoder shaft. Although a “Marker” pulse is standard on some encoders, it is additional feature (charge) on many encoders. Ask for one, if you need one. Confidential