Product Analysis: Heidenhain 385438-87 (ERN 1387)
The Heidenhain 385438-87 is a specialized incremental rotary encoder from the ERN 1300 series. The ERN 1387 is globally recognized as the industry standard for feedback in elevator (lift) motors and traction drives. It is specifically designed to provide high-resolution position data and commutation signals for permanent-magnet synchronous motors (PMSM), ensuring smooth acceleration and comfortable ride quality for passengers.
High-Resolution Feedback and Commutation
This encoder provides 2048 pulses per revolution through a 1Vpp sinusoidal signal. In addition to the standard incremental tracks, the ERN 1387 features a unique Z1 track (commutation signals), which provides one sine/cosine period per revolution. This allows the drive inverter to determine the absolute position of the motor rotor within one revolution upon startup, which is critical for the proper torque control of elevator motors.
Technical Characteristics
- Part Number: 385438-87.
- Series: ERN 1387.
- Pulses per Revolution: 2048.
- Output Signal: 1Vpp (Sin/Cos).
- Commutation Signal: 1 sine/cosine period per revolution (Z1 track).
- Shaft: Tapered shaft 1:10 (9.25mm).
- Power Supply: 5V DC (+/- 5%).
- Mechanical Connection: Stator coupling for easy mounting.
Engineering Excellence for Traction Drives
The 385438-87 is built to withstand the continuous operational cycles and thermal variations found in elevator machine rooms. Its optical scanning technology ensures that the commutation signals are perfectly aligned with the motor windings, preventing motor «cogging» or vibration. The 1Vpp interface is highly resistant to electrical noise, which is common in high-power motor control environments.
| Category | Specification |
| System Accuracy | ±20″ |
| Cut-off Frequency | 210 kHz (-3 dB) |
| Operating Temperature | -40°C to +120°C |
Frequently Asked Questions
Can I use this encoder in a CNC spindle? While possible, the ERN 1387 is specifically optimized for elevator applications. For CNC spindles, the ERN 1381 or ERN 1387 with higher speed ratings is usually preferred. Does it require a specific cable? Yes, the 1Vpp signal with commutation requires a high-quality shielded 12-core cable to prevent signal loss over distance.
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