Eltra EH 53 Hollow Shaft Incremental Encoder

Name: Eltra EH 53 Hollow Shaft Incremental Encoder | Seven Star
Brand: Eltra
SKU: EH 53

A compact blind hollow shaft encoder with integrated elastic coupling for direct motor mounting

The EH 53 is a 53 mm class incremental encoder for mounting straight onto a motor shaft. Its integrated elastic coupling absorbs radial and axial shaft play, so the encoder does not need a separate coupling or a precisely machined mounting face. The datasheet lists a three channel A / B / Z output, up to 1024 pulses per revolution, a supply of up to 24 V DC and an output frequency of up to 150 kHz.

Two flange styles exist, the adjustable flange model 53A and the adjustable flange model 53B, and the blind bore can be 6, 8 or 10 mm. The housing is glass-fibre reinforced PA66 and the output is a short radial cable with connectors added at the cable end, which keeps the weight to 150 g. It suits small AC motors, geared motors and general machinery in workshops and plants where the environment is dry and enclosed.

Main features from the manufacturer

Direct mounting on motors with an integrated elastic coupling
Allows radial and axial shaft play
Three channel output (A / B / Z) up to 1024 ppr
Supply up to +24 V DC; NPN, push-pull and line driver interfaces
Output frequency up to 150 kHz
Bore diameters 6, 8 and 10 mm
Cable output, connectors available on the cable end

Technical specifications

Parameter	Specification
Models	Adjustable flange 53A and 53B
Resolution	100 to 1024 ppr in the specification table; the ordering code and the pulse list start at 50 ppr
Supply voltage	5 version: 4.5 to 5.5 V DC; 8/24 version: 7.6 to 25.2 V DC with reverse polarity protection
Current consumption	100 mA max without load
Max load current	C / P 50 mA per channel; L 20 mA per channel
Output circuits	NPN open collector (pull-up max +30 V DC); push-pull HTL; line driver RS-422
Max output frequency	150 kHz
Counting direction	A leads B clockwise, shaft view
Index signal	180°e, gated A
Bore diameter	6, 8 or 10 mm, blind
Enclosure rating	IP 54 (IEC 60529)
Max rotation speed	6000 rpm
Shock / vibration	50 G, 11 ms / 10 G, 10 to 2000 Hz
Moment of inertia	1 x 10-6 kgm2
Starting torque	Below 0.01 Nm at +20°C
Materials	Bearing stage aluminum; shaft stainless steel; housing PA66 glass fibre reinforced
Bearings	2 ball bearings, life 109 revolutions
Cable	Shielded, fixed installation, 0.22 mm2 (AWG 24), min bend radius 60 mm
Operating temperature	-10 to +60°C at the flange; no condensation
Storage temperature	-25 to +70°C
Weight	150 g
MTTFd / mission time	208 years / 20 years per EN ISO 13849-1; DC 0 %
Approvals printed	UL / CSA file E212495; EMC 2014/30/EU; RoHS 2011/65/EU

EH 53 ordering code explained

The datasheet example is EH 53A 500 S 8/24 P 8 X 6 PR.N .XXX, which breaks down as follows.

Code position	Options
Model	53A or 53B adjustable flange
Resolution	50 to 1024 ppr; listed values include 50, 100, 120, 125, 128, 150, 180, 200, 250, 256, 300, 360, 400, 500, 512, 600, 720, 1000, 1024
Zero pulse	S without, Z with
Power supply	5 V DC with L interface; 8/24 for 8 to 24 V DC
Electrical interface	C NPN open collector; P push-pull; L line driver
Bore	6, 8 or 10 mm
Enclosure / speed	X = IP 54 / 6 = 6000 rpm
Output type	PR.N radial cable, 0.5 m standard; 1.5, 2, 3, 5 or 10 m optional
Variant	XXX custom version

Installation and operating notes

Fit the encoder on a shaft with a g6 tolerance, as recommended in the datasheet. The built-in coupling is intended to take up shaft play, so the stator should be fixed through the flange without forcing a rigid second support.

The Z index is 180 electrical degrees wide and gated with channel A. If the controller expects an index gated with both A and B, check this against the input specification of the counter or drive.

Cable core colours are red +V DC, black 0 V, green A+, yellow B+ and blue Z+, with brown or grey, orange and white as the inverted channels on the line driver version.

Motor feedback and light machinery use

The EH 53 is described for direct mounting on motors. In practice that means small AC motors, conveyor and packaging drives, fans, mixers and test rigs where a low-cost speed or position signal is needed and the rating of IP 54 is enough.

Because the bearing life, housing material and operating range are modest compared with metal-cased series, treat it as an indoor product. For hot or wet exteriors in the Gulf climate, compare the Eltra series with higher IP ratings listed elsewhere in the catalogue. This remark is general guidance.

Information to send with an RFQ for the Eltra EH 53

To quote the right EH 53, send the points below.

Model 53A or 53B and the motor shaft diameter (6, 8 or 10 mm)
Required ppr, zero pulse yes or no
Supply voltage and output circuit expected by the drive or PLC
Cable length and any connector fitted at the cable end

Commissioning and maintenance notes

Check that the encoder output type and supply voltage match the drive or counter input before connecting it, and use shielded cable with the shield earthed as described in the manual. In the region, motors often run in hot plant rooms or outdoors, so check the encoder’s operating temperature against the real conditions near the motor, including heat from the motor itself. Inspect the connector and cable during routine maintenance.

When replacing an encoder, record the resolution and output type of the old unit, so the replacement matches without changes to the drive settings.

Frequently asked questions

What bore sizes does the EH 53 offer?

6, 8 and 10 mm blind bores.

What is the maximum resolution and frequency?

The datasheet gives up to 1024 ppr and an output frequency of up to 150 kHz.

How is the encoder coupled to the shaft?

Through an integrated elastic coupling that allows radial and axial shaft play.

What enclosure rating applies?

IP 54 according to IEC 60529.

What supply voltages are available?

4.5 to 5.5 V DC for the 5 version and 7.6 to 25.2 V DC for the 8/24 version.

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