EncoderWorks develops the FGH6KK-2500G-90G-NG-S-J/50P custom compatible replacement solution around heavy-duty incremental speed feedback where 2500 PPR scaling, A/B 90° quadrature, inverted signal pairs, NG reference-pulse behavior, dual terminal-box wiring, programmable overspeed switching, reduced rotational-frequency modulation, and Ø50 H7 hollow-shaft fit must remain stable at the installed counter. The failure boundary is not a fieldbus telegram or an absolute position word, but wrong pulse scaling, missed edges, phase jitter, reference mismatch, overspeed switch inconsistency, output-driver incompatibility, shield noise, shaft-current exposure, and hollow-shaft movement. Typical production lead time: 15 working days.
This model is used where a large hollow-shaft incremental encoder is mounted directly on a heavy machine shaft for speed measurement, direction recognition, indexing, process synchronization, and speed-limit monitoring. A compatible replacement must preserve the 2500 pulses per revolution, 90° phase relationship, inverted A/B/N signal requirement, terminal-box assignment, output level, overspeed switch function, J option behavior, 50P bore geometry, housing ground path, and heavy-duty mounting boundary.
System Limits
The first system boundary is the 2500 PPR counter interface and overspeed-switch logic. FGH6KK-2500G-90G-NG-S-J/50P must be checked against maximum input frequency, edge evaluation, A/B direction logic, reference-pulse width, inverted-signal use, output-driver type, supply level, cable length, overspeed thresholds, switching delay, switching hysteresis, diagnostics expectation, and the reduced rotational-frequency modulation requirement. If the replacement is supplied as 2000 PPR, 2048 PPR, 4096 PPR, or without the correct inverted and reference channels, the controller may still count pulses while speed scaling, travel calculation, direction detection, homing, or overspeed monitoring becomes unreliable.
The second boundary is the KK dual-terminal and Ø50 hollow-shaft installation. Each terminal box, 0 V reference, shield path, cable gland, housing bond, PE continuity, and overspeed wiring path must be treated as part of the measurement system. A correct encoder can still fail if one terminal box has a weak shield connection, signal cables run beside brake or drive wiring, duplicated signal paths are grounded differently, or the Ø50 H7 hollow shaft is fitted with eccentric load. The 50P bore, keyway fit, axial movement, torque reaction, vibration, bearing load, and optional shaft-current isolation requirement should be checked together.
Wiring & Installation
Before replacement, confirm the full installed model code, 2500 PPR requirement, A/B 90° relationship, NG reference-pulse use, inverted output requirement, output circuit, supply voltage, counter frequency margin, dual terminal-box layout, cable-entry direction, shield termination method, overspeed switch settings, J option requirement, and Ø50 H7 hollow-shaft dimension. This version should not be treated as the non-S variant because overspeed thresholds, switch wiring, diagnostic behavior, and commissioning checks add a separate failure boundary.
During installation, verify A, B, reference, inverted channels, supply, 0 V, shield, housing ground, both terminal-box paths, and overspeed switch wiring before powering the system. Keep signal cables away from motor, brake, SCR, and VFD wiring, and do not use the cable shield as a load-carrying ground conductor. The hollow shaft must seat concentrically on the machine shaft, and the torque restraint should prevent encoder-body movement without forcing the bearing system. Eccentric preload can become phase jitter, bearing wear, unstable reference repeatability, speed-feedback noise, or nuisance overspeed trips.
Custom Compatible Solution
- Match 2500 PPR incremental feedback, A/B 90° quadrature, inverted A/B/N signals, NG reference behavior, and controller counter expectations
- Preserve dual terminal-box wiring, shield continuity, output-driver compatibility, supply reference, overspeed switch function, diagnostic boundary, and J option signal stability
- Adapt the Ø50 H7 hollow shaft, keyway fit, heavy-duty housing, bearing-load boundary, torque restraint, cable entry, and machine-side mounting geometry
- Review counter frequency margin, overspeed settings, switching delay, EMC exposure, shaft-current risk, runout, vibration, and commissioning checks before shipment
Key Data
| Item | Data |
|---|---|
| Model | FGH6KK-2500G-90G-NG-S-J/50P |
| Encoder type | Heavy-duty large hollow-shaft incremental encoder |
| Feedback type | Incremental A/B with reference pulse |
| Pulse count | 2500 PPR |
| Phase relationship | A/B, 90° quadrature |
| Inverted signals | G, inverted output signal boundary |
| Reference pulse | NG reference pulse with inverted signal |
| Overspeed option | S, electronic overspeed switch requires setting confirmation |
| Signal quality option | J, reduced rotational-frequency modulation boundary |
| Connection | KK, dual terminal boxes with terminal strips |
| Shaft interface | 50P, Ø50 H7 hollow shaft with keyway |
| Output circuit | HTL / TTL or installed output level requires confirmation |
| Supply voltage | 12–30 VDC, installed version requires confirmation |
| Protection boundary | Up to IP66, sealing and speed limit require installed-version confirmation |
| Key system checks | 2500 PPR scaling, counter frequency, A/B direction, NG reference, inverted channels, overspeed thresholds, J option, shield grounding |
| Key mechanical checks | Ø50 bore fit, keyway fit, runout, axial movement, torque restraint, vibration, bearing load, shaft-current isolation requirement |
