EncoderWorks builds the FGH4K-1024G-90G-NG/20P custom compatible replacement solution around heavy-duty incremental feedback where 1024 PPR scaling, A/B 90° quadrature, NG reference-pulse behavior, terminal-box wiring, shield continuity, and 20 mm hollow-shaft fit must remain stable at the installed counter. The failure boundary is not a fieldbus telegram or an absolute position word, but missed counts, phase jitter, reference-pulse mismatch, output-driver incompatibility, ground noise, hollow-shaft runout, and torque-reaction movement. Typical production lead time: 15 working days.
This model is used where the machine controller reads speed, direction, and relative position from A/B incremental channels and uses the NG reference pulse for indexing or homing. A compatible replacement must preserve the 1024 pulses per revolution, 90° channel separation, reference-pulse location, inverted reference requirement, output level, terminal assignment, shield path, 20P bore interface, and heavy-duty mechanical boundary.
System Limits
The first system boundary is the pulse count and counter interface. FGH4K-1024G-90G-NG/20P must be checked against the controller’s edge evaluation mode, maximum input frequency, expected A/B direction, reference-pulse width, output-driver type, and inverted-signal requirement. If the replacement is supplied as 1200 PPR, 1000 PPR, or another nearby resolution, the encoder may still produce clean pulses while the machine position, speed scaling, or indexing point becomes wrong. Typical failures include accumulated position error, reversed direction logic, missed reference detection, unstable homing, or drift after high-speed operation.
The second boundary is the hollow-shaft and EMC installation. Terminal-box wiring, 0 V reference, shield bonding, cable routing, and housing ground must be treated as part of the measurement circuit. A correct encoder can still fail if the cable shield is grounded through a high-impedance path, the signal cable is routed beside brake or inverter wiring, the terminal box loses PE continuity, or the 20 mm hollow shaft is clamped with eccentric load. Mechanical checks should include bore fit, shaft runout, axial movement, torque-reaction restraint, vibration, and bearing load.
Wiring & Installation
Before replacement, confirm the complete installed model code, 1024 PPR requirement, A/B phase relationship, NG reference-pulse use, inverted reference requirement, output circuit, supply voltage, terminal-box layout, cable entry direction, shield termination method, and 20 mm hollow-shaft dimension. This model should not be inferred from solid-shaft FG4 versions or from absolute encoder families because the controller depends on pulse timing and edge quality rather than digital position data.
During installation, verify A, B, reference, inverted reference if used, supply, 0 V, shield, and housing ground before powering the system. Keep the signal cable away from motor, brake, SCR, and VFD wiring, and avoid using the cable shield as a load-carrying ground conductor. The hollow shaft must sit concentrically on the machine shaft, and the torque-reaction element should stop encoder-body rotation without forcing the bearing system. Eccentric preload can become phase jitter, bearing wear, or poor reference-pulse repeatability.
Custom Compatible Solution
- Match 1024 PPR incremental feedback, A/B 90° quadrature, NG reference-pulse behavior, and controller counter expectations
- Preserve output-driver compatibility, terminal-box wiring, supply reference, inverted-signal requirement, shield path, and grounding continuity
- Adapt the 20 mm hollow shaft, heavy-duty housing, bore fit, torque-reaction boundary, cable entry, and machine-side mounting geometry
- Review counter frequency margin, homing behavior, EMC exposure, shaft runout, vibration, and commissioning checks before shipment
Key Data
| Item | Data |
|---|---|
| Model | FGH4K-1024G-90G-NG/20P |
| Encoder type | Heavy-duty hollow-shaft incremental encoder |
| Feedback type | Incremental A/B with reference pulse |
| Pulse count | 1024 PPR |
| Phase relationship | A/B, 90° quadrature |
| Reference pulse | NG reference pulse with inverted signal requirement |
| Shaft interface | 20 mm hollow shaft / 20P bore |
| Connection boundary | Terminal-box wiring requires confirmation against installed version |
| Output circuit | Requires confirmation against controller input |
| Supply voltage | Requires confirmation against installed version |
| Key system checks | Counter frequency, edge evaluation, A/B direction, reference pulse, inverted signal, shield grounding, terminal-box PE continuity |
| Key mechanical checks | Bore fit, shaft runout, torque reaction, axial movement, vibration, bearing load |
| Replacement focus | 1024 PPR scaling, NG reference behavior, EMC grounding, 20 mm hollow-shaft stability |
