Eltra EF 36 K Hollow Shaft Servo Encoder with Hall Phases

A 36 mm servo feedback encoder with six channels and optical Hall phases

The EF 36 K is a 36 mm blind hollow shaft encoder for feedback control of AC servomotors. Eltra describes it as interchangeable with a size 15 resolver at the rear of the motor. Besides the usual A / B / Z incremental channels it generates optical “Hall effect phases”, the U, V and W commutation signals, so the drive knows the rotor position from power-up without a separate Hall sensor.

It is a six channel encoder with signals transmitted via a bit-parallel bus. The motor pole count is part of the code (4, 6 or 8 poles), so the commutation pattern is matched to the motor. Incremental resolution is 500 to 1024 ppr, supply is 5 V DC, and the body is aluminum with a stainless steel shaft and a rear-fixing flange. The datasheet lists a high temperature resistance of up to +85°C.

What this encoder offers

• 36 mm series recommended for AC servomotor feedback
• Interchangeable with size 15 resolver at the motor rear
• Six channel encoder with optical Hall effect phases
• Signal transmission via bit-parallel bus
• Easy mechanical mounting and small dimensions
• Wide range of resolutions and high temperature resistance

Technical specifications

EF 36 K ordering code and cable connections

The datasheet example is EF 36K 4 L 512 S 5 L 8 X 6 PR . XXX.

Installation and operating notes

The datasheet shows the 4 mm torque pin position (at least 0.5 mm from the bottom end) and refers to the Accessories list for the size 15 resolver flange. The mating shaft tolerance is g6.

Match the pole count to the motor. The code lists which resolution is possible with which pole count, so a 1000 ppr encoder is not available on a 4-pole motor.

The enclosure rating of IP 40 and the 5 G vibration rating mean the encoder must sit inside a closed motor housing and not on a vibrating exposed shaft end.

Applications for the EF 36 K

The EF 36 K is used where a brushless servomotor needs incremental feedback plus commutation signals from one compact device: small servo axes, handling and positioning drives and spindle motors, particularly when upgrading a motor that used a size 15 resolver.

Since the datasheet describes only IP 40, it is for installation inside the motor. General guidance for sandy or humid GCC plants: choose a motor housing that provides the sealing.

Information to send with an RFQ for the Eltra EF 36 K

To quote the EF 36 K we need these details.

• Motor pole count (4, 6 or 8) and incremental resolution
• Bore diameter, and whether a resolver flange adapter is needed
• Commutation signal type, NPN or line driver
• Cable length and drive manufacturer for the signal check

Related items and documents

For hollow shaft encoders without commutation signals see the Eltra EH 50 page. Visit the encoders category for neighbouring products. The datasheet is linked above. Seven Star LLC answers EF 36 K requests when you supply the ordering code and the quantity.

Commissioning and maintenance notes

Servo feedback encoders of this type are used in the region by machine builders and maintenance teams on AC servo motors in packaging, printing, textile and automation equipment. When replacing a resolver or another encoder, check that the servo drive supports incremental feedback with Hall phases and that the number of motor poles matches the encoder’s Hall phase configuration. Before installation, check that the bore matches the motor shaft, and avoid hammering the encoder onto the shaft.

The Hall phase alignment with the motor must be set as described in the manual or the drive documentation, otherwise the motor will not commutate correctly. Use shielded cable with the shield earthed, kept away from motor power cables. In hot machine enclosures, check the operating temperature against the real conditions near the motor, and inspect the connector and cable during routine maintenance.

When ordering a replacement, record the resolution, the number of poles, the bore and the connection of the existing encoder, so the new unit fits the motor and drive without changes. Keeping one spare encoder for critical servo axes shortens downtime.

Related Eltra products: Eltra EH 80 C/K/P/PG Hollow Shaft Encoder for AC Servo Motors, Eltra EL 63 Compact Hollow Shaft Incremental Encoder, 35 mm Height, Eltra EH 53 A/B Blind Hollow Shaft Incremental Encoder, Eltra EH 88 PE/PET Large-Bore Hollow Shaft Encoder, up to 40 mm, Eltra EH 50 FA/FP Through Hollow Shaft Incremental Encoder and Eltra ER 38 F/G Miniature Blind Hollow Shaft Incremental Encoder.