Eltra EH 88 PE/PET Large-Bore Encoder

Name: Eltra EH 88 PE/PET Large-Bore Encoder | Seven Star LLC
Brand: Eltra
SKU: EH 88

A large-bore through hollow shaft encoder for elevators, stage machinery and asynchronous motors

The EH 88 is the large-bore member of the Eltra EH family. The datasheet calls it a cost effective encoder for asynchronous motors, suitable for elevators and stage machinery, with a sturdy mechanic and a bore diameter of up to 40 mm. Bores of 25, 30, 35, 38 and 40 mm let it sit on the free shaft end of a geared elevator machine or a larger motor without an adapter.

There are two models. The EH 88PE has a torque stop slot, and the EH 88PET is prepared for fixing with a torque arm that is ordered separately. Resolution runs from 500 to 2500 ppr, with a three channel A / B / Z output, up to 30 V DC supply, line driver or push-pull interface and an output frequency of up to 105 kHz. The shaft is fixed by collar clamping.

Feature summary

Cost effective encoder for asynchronous motors
Suitable for elevators and stage machinery
Three channel output (A / B / Z) up to 2500 ppr
Supply up to +30 V DC; push-pull and line driver interfaces
Output frequency up to 105 kHz
Bore diameter up to 40 mm with collar clamping
Sturdy mechanic, cable output with connectors on the cable end

Technical specifications

Parameter	Specification
Models	88PE with torque stop slot; 88PET for torque arm fixing (arm not included)
Resolution	500 to 2500 ppr (500, 512, 720, 1000, 1024, 1440, 2500)
Supply voltage	5 version: 4.5 to 5.5 V DC; 5/28 version: 4.5 to 30 V DC with reverse polarity protection
Power draw without load	0.8 W max
Max load current	20 mA per channel
Output circuits	Push-pull HTL; line driver RS-422
Max output frequency	105 kHz
Index signal	90°e, gated A and B
Bore diameter	25, 30 mm (both models); 35, 38, 40 mm (PE only)
Enclosure rating	IP 54 (IEC 60529)
Max rotation speed	3000 rpm
Shock / vibration	50 G, 11 ms / 10 G, 10 to 2000 Hz
Moment of inertia	45 x 10-6 kgm2
Starting torque	Below 0.02 Nm at +20°C
Materials	Housing and bearing stage aluminum; shaft aluminum up to 38 mm and stainless steel at 40 mm
Bearings	2 ball bearings, life 109 revolutions
Cable	Shielded, fixed installation, 0.22 mm2, min bend radius 60 mm
Operating and storage temperature	-30 to +85°C; no condensation
Weight	350 g
MTTFd / mission time	220 years / 20 years per EN ISO 13849-1; DC 0 %
Approvals printed	UL / CSA file E212495; EMC 2014/30/EU; RoHS 2011/65/EU

Ordering code for the EH 88

The datasheet example is EH 88PE 1024 S 5/28 P 30 X 3 PR . XXX.

Code position	Options
Model	88PE (torque stop slot) or 88PET (torque arm fixing)
Resolution	500, 512, 720, 1000, 1024, 1440 or 2500 ppr
Zero pulse	S without, Z with
Power supply	5 V DC with L interface; 5/28 for 5 to 28 V DC
Electrical interface	P push-pull; L line driver; RS 5/28 V DC supply with RS-422 output
Bore	25, 30 mm; 35, 38, 40 mm for 88PE only
Enclosure / speed	X = IP 54 / 3 = 3000 rpm
Output type	PR radial cable, 0.5 m standard; 1.5, 2, 3, 5 or 10 m optional

Installation and operating notes

Use a g6 mating shaft. The torque arm or torque pin is an accessory, so order it with the encoder; the 88PET cannot be installed without a torque arm.

Because the housing is much heavier in inertia terms than small encoders (45 x 10-6 kgm2), keep the torque reaction stiff but not over-constrained, so that thermal growth of the motor shaft does not load the bearings.

The 2500 ppr and 105 kHz limits together allow about 2500 rpm at full resolution (derived: 105000 x 60 / 2500 = 2520 rpm), below the 3000 rpm mechanical rating; at 1024 ppr the pulse limit is not reached.

Applications for the EH 88

The datasheet names elevators and stage machinery. In the Gulf this includes building lift machines, escalator and travelator drives, theatre and event rigging, and general geared motors where a large bore is needed.

The enclosure is IP 54 and the operating range -30 to +85°C, so mount the encoder in a machine room or motor fan cover rather than in direct sun or spray. This is general guidance.

Information to send with an RFQ for the Eltra EH 88

Send the information below to get a quotation for the EH 88.

Model 88PE or 88PET and shaft diameter (25 to 40 mm)
Resolution and zero pulse
Supply voltage and output circuit
Cable length and torque arm requirement

Commissioning and maintenance notes

Large-bore hollow shaft encoders are used in the region on lift and escalator motors in buildings, on stage machinery in theatres and event venues, and on asynchronous motors driving cranes, conveyors, pumps and fans in industry. Before installation, check that the bore matches the shaft, using the correct reducing sleeve where needed, and that the anti-rotation arm or spring is fixed so it does not load the bearings. Avoid hammering the encoder onto the shaft, as shocks can damage the optical disc and bearings.

Match the output type and supply voltage with the drive or controller input, and use shielded cable with the shield earthed as described in the manual, kept away from motor power cables. Lift machine rooms and plant rooms in the region can become hot in summer, so check the operating temperature against the real conditions near the motor. Inspect the connector, cable and fixing during routine maintenance, and replace damaged cables at once to avoid lost pulses and drive faults.

When ordering a replacement, record the resolution, output type, bore and connection of the existing encoder, so the new unit fits without changes to the drive settings. Keeping one spare encoder for critical lifts or machines shortens downtime.

Frequently asked questions

What bore sizes does the EH 88 offer?

25, 30, 35, 38 and 40 mm, with 35, 38 and 40 mm limited to the 88PE model.

What applications does the datasheet name?

Asynchronous motors, elevators and stage machinery.

Is the torque arm included?

No. The 88PET needs a torque arm that is listed under Accessories.

What resolutions are available?

500, 512, 720, 1000, 1024, 1440 and 2500 ppr.

What temperature range applies?

-30 to +85°C for operation and storage.

Encoders for motors, lifts and machinery

Eltra describes application areas such as industrial automation, motor feedback, lift systems, packaging, light material processing, heavy duty industry, off-highway vehicles and potentially explosive atmospheres. Hollow shaft and solid shaft designs, bore sizes from a few millimetres to 40 mm, resolutions up to 24000 ppr and enclosure ratings up to IP 67 are printed in the Eltra datasheets.

Frequently Asked Questions