EncoderWorks develops the FGH4K-1200G-90G-NG/20P custom compatible replacement solution around heavy-duty incremental feedback where 1200 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 address or an absolute data word, but missed counts, phase jitter, reference-pulse misalignment, output-driver mismatch, 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 position incrementally from A/B channels and a reference pulse. A compatible replacement must preserve the 1200 pulses per revolution, 90° channel separation, NG zero-pulse requirement, electrical output level, terminal assignment, cable shield path, 20P hollow-shaft interface, and heavy-duty installation boundary.
System Limits
The first system boundary is the counter and signal interface. FGH4K-1200G-90G-NG/20P must be checked against the controller’s maximum input frequency, expected edge evaluation, output voltage level, line-driver type, reference-pulse width, and use of inverted signals. If the replacement is supplied with the wrong PPR, wrong A/B direction, unstable 90° phase separation, missing NG reference, or an output driver that does not match the counter input, the system may run but lose counts, reverse direction logic, fail homing, or show position drift after speed changes.
The second boundary is the hollow-shaft and EMC installation. Terminal-box wiring, 0 V reference, shield bonding, cable routing, and housing grounding must be treated as part of the measurement system, not as accessories. A correct encoder can still fail if the shield is grounded through a high-impedance path, the signal cable runs beside brake or inverter wiring, the terminal box loses PE continuity, or the 20 mm hollow shaft is clamped under eccentric load. Mechanical checks should include bore fit, shaft runout, axial movement, torque-reaction restraint, and vibration at the mounting point.
Wiring & Installation
Before replacement, confirm the full installed model code, 1200 PPR requirement, A/B phase relationship, NG reference-pulse use, 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 variants or from absolute encoder families because the controller depends on pulse timing and edge quality rather than digital position telegrams.
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 prevent encoder-body rotation without forcing the bearing system. Any eccentric preload can turn into phase jitter, bearing wear, or intermittent reference-pulse repeatability.
Custom Compatible Solution
- Match 1200 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-1200G-90G-NG/20P |
| Encoder type | Heavy-duty hollow-shaft incremental encoder |
| Feedback type | Incremental A/B with reference pulse |
| Pulse count | 1200 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 | 1200 PPR scaling, NG reference behavior, EMC grounding, 20 mm hollow-shaft stability |
