Inductive encoder
LTN frameless resolvers inductive encoder
Brushless frameless (kit) resolvers in 36.83, 50.77 and 71.02 mm outside diameters with 1 to 5 pole pairs, 6 to 10 arcmin accuracy, up to 20,000 rpm and -55 to +155 °C, now produced and sold by HEIDENHAIN.
Key specifications
| Outer diameter | 36.83–71.02 mm |
|---|---|
| Temperature | -55–155 °C |
| Speed (max) | 20,000 rpm |
| Accuracy | 6 to 10 arcmin |
| Pole pairs | 1 to 5 |
| Principle | brushless resolver, inductive signal transfer |
Summarised in our own words from HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026)'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1 · Source 2
Notes on this data
Resolvers classed under 'inductive' as the closest allowed encoder type. LTN Servotechnik GmbH ceased operations on 30 April 2026; HEIDENHAIN continues LTN resolvers.
Specify Motion is not affiliated with HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026). LTN Servotechnik and LTN frameless resolvers are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a LTN Servotechnik part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 2 series from our supply network are the closest match on published figures.
Celera Motion (Zettlex) non-contact inductive absolute angle encoder in 37 and 58 mm sizes, sealed to IP67, -60 to +105 C.
View Mini Ultra IncOder →Larger-bore Zettlex inductive absolute encoder from 75 to 300 mm OD with up to 22-bit resolution.
View Midi Ultra IncOder →Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What an inductive encoder is
An inductive encoder measures position using coils printed on circuit boards: a transmitter coil creates an alternating magnetic field, and receiver coils pick up how a conductive target or rotor pattern modifies it as it moves. Electronics convert the signals into absolute position. With no optics, magnets or contacting parts, inductive encoders are highly tolerant of dirt, water, oil, shock and temperature. They are typically non-contact, bearingless and available in ring formats with large bores.
When engineers choose an inductive encoder
Choose an inductive encoder for harsh environments where optical encoders would be blinded and magnetic encoders could be disturbed, such as defence, aerospace, oil and gas, subsea and heavy mobile machinery. Large-bore rings suit gimbals and turrets. The trade-offs are resolution and cost: inductive encoders are typically less finely resolving than high-end optical encoders and may cost more than magnetic ones. Mounting is tolerant but still needs control.
How to specify the LTN frameless resolvers
Send these with your enquiry and an engineer can confirm the right LTN frameless resolvers variant or an equivalent:
- Absolute resolution (bits)
- Accuracy (arcmin or arcsec)
- Outer diameter and bore (mm)
- Interface: SSI, BiSS or analogue
- Temperature range (°C)
- Shock and vibration requirements (g)
- Sealing and IP code
Common mistakes to avoid
- Mounting conductive parts too close to the sensing area
- Ignoring the encoder's permitted gap and alignment tolerances
- Expecting top optical resolution
- Overlooking EMC near high-power cables
LTN frameless resolvers: frequently asked questions
What is the LTN frameless resolvers?
Brushless frameless (kit) resolvers in 36.83, 50.77 and 71.02 mm outside diameters with 1 to 5 pole pairs, 6 to 10 arcmin accuracy, up to 20,000 rpm and -55 to +155 °C, now produced and sold by HEIDENHAIN. Published series figures include outer diameter 36.83 mm, outer diameter 71.02 mm, temperature -55 °C, temperature 155 °C. It is made by HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026); Specify Motion can help source it or propose an equivalent.
Who makes the LTN frameless resolvers?
The LTN frameless resolvers is made by LTN Servotechnik (HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026)) and is listed here for engineers comparing options. Specify Motion is not affiliated with HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026); brand names are used only to identify the product.
What is the outer diameter of the LTN frameless resolvers?
The published series minimum outer diameter is 36.83 mm. Individual models and sizes in the LTN frameless resolvers range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the LTN frameless resolvers?
Yes. On published figures, Novanta Mini Ultra IncOder and Novanta Midi Ultra IncOder are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
How is an inductive encoder different from a magnetic encoder?
An inductive encoder uses printed coils and a conductive target, not permanent magnets, so it is not disturbed by stray magnetic fields and contamination in the same way. Magnetic encoders use magnets and Hall or magnetoresistive sensors, which are cheaper but can be affected by external fields.
Can inductive encoders operate underwater?
Many inductive encoders can be fully potted or sealed and are tolerant of water, oil and dirt, which suits subsea and wet applications. The sealing, connector and depth rating must be specified. Check that the specific product is qualified for immersion.
Further reading: How to select an encoder · Magnetic vs capacitive vs optical encoders · Encoders and feedback
Other inductive encoder series
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