New Motor-Mount Encoder Helps Reduce Downtime


A new motor-mount encoder designed to reduce large motor downtime by means of an exceptional shaft seal, unbreakable code disc, and optional redundant outputs. The new HSD35 encoder is one of the few hollowshaft encoders to use optical technology combined with field serviceable connectors.

The new encoder was specially designed for use in the vector motor market, where the uptime of large motors has a significant impact on mill and plant productivity. Mounting options include stamped metal or swivel ball tethers for TEFC or C-face mounting.

The new HSD35 encoder replaces the obsoleted NorthStar MagCoder but with significant improvements. The HSD35 encoder incorporates a popular field-serviceable EPIC connector requiring no special tools or soldering irons for connection — a simple slotted screwdriver is all that’s needed. Conduit or cable can be wired directly to the encoder via a ½-inch NPT connection. In addition, new shaft seals provide improved resistance to penetration from water

and abrasive particulate matter. Although the overall rating of the unit is a stout washdown IP65/NEMA 4, the shaft seals themselves are proven to the more stringent IP67. (A sister product, the HS35 encoder, is rated to the full IP67 rating.) Use of the included back-end shaft cover and mating gasket makes the unit even more resistant to contamination.

Unlike other encoders that use glass code discs to achieve high resolution, the HSD35 encoder uses a new unbreakable disc made of a highly engineered plastic, currently offered on the 2048 PPR resolution model. (Lower resolution models use an unbreakable metal disc). This particular resolution is becoming more popular with drive manufacturers because of its ability to provide smooth speed control at lower motor RPMs.

Optional Dual Outputs Increase Reliability
In most vector motor applications, encoder feedback for the drive is a must for tight speed tolerance. However, more and more applications require a second encoder signal routed to a piece of process equipment, such as a digital display or counter. Often, more than one encoder must be used, or at minimum, a signal splitter is required. Optional dual outputs on the HSD35 and HS35 encoders solve this common problem by enabling both the drive and secondary equipment to operate off the same encoder.

In applications requiring only one encoder signal output, the second output acts as a built-in spare, assuring that communication will continue in the event that the first signal is damaged. For reliability, the two outputs are powered separately and are electrically isolated.

A multitude of English and metric shaft bore sizes are available, with a wide range of voltages and outputs for drive electrical requirements. The added bonus of an electrically isolated shaft helps reduce the worry of shaft currents being grounded through the encoder, potentially damaging bearings or internal electronics. In addition, CSA certification for hazardous duty is pending.

Dynapar will market the HSD35 under its NorthStar brand name, and its sister product, the HS35, will continue to be marketed under the Dynapar name.

Cost and Availability
The NorthStar HSD35 and Dynapar HS35 encoders are available now through Dynapar distribution channels in the U.S. and abroad, typically ship within three business days. List prices start at $535 for the HSD35 and $363 for the HS35.


• Code: Incremental • Resolution: 1 to 2500 PPR (pulses/revolution) • Accuracy: (worst case any edge to any other edge) ±7.5 arc-min. • Format: Two channel quadrature (AB) with optional Index (Z) and complementary outputs • Phase Sense: A leads B for CW shaft rotation viewing the shaft clamp end of the encoder • Quadrature Phasing: 90° ± 22.5° electrical • Symmetry: 180° ± 18° electrical • Index: 180° ± 18° electrical (gated with B low) • Waveforms: Squarewave with rise and fall times less than 1 microsecond into a load capacitance of 1000 pf
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