For FGH4KK-2000G-90G-NG/20P, EncoderWorks can configure a custom compatible replacement solution only if the 2000 PPR glass-disk scaling, KK redundant dual terminal-box layout, /20P hollow-shaft fit, A/B 90° phase relationship, inverted signal pairs, N marker behavior, torque bracket freedom, adapter-shaft run-out, and shielded signal transmission remain matched. The main failure boundary is a hollow-shaft feedback system that receives pulses but reports wrong travel, speed deviation, redundant-channel mismatch, or zero-reference loss because the pulse class, terminal-box wiring, bore fit, or torque support has changed. Typical production lead time: 15 working days.
This model belongs to the FGH 4 hollow-shaft incremental encoder platform. The 2000 PPR value should be treated as a preferred glass-disk pulse rate, so replacement work should focus on glass-disk edge stability, counter frequency margin, redundant channel agreement, A/B/N signal continuity, and controlled hollow-shaft mounting. It should not be treated as a solid-shaft FG 4 encoder or as an FGH40 configuration with different electrical limits.
System Limits
The first system limit is 2000 PPR glass-disk scaling. If the controller is configured for 2048, 1200, 2500, 4096, or another pulse count, both terminal-box outputs may look electrically stable while speed, travel, and synchronization values become wrong. Edge-counting mode, gear ratio, direction logic, and machine conversion factors should be confirmed on both feedback paths.
The second limit is KK redundant terminal-box agreement. Each terminal box must preserve A, /A, B, /B, N, and /N exactly as expected by the controller or comparison circuit. If one phase pair is swapped, one inverted output is omitted, one shield reference differs, or the N marker is wired differently between boxes, the machine may fail during homing, direction reversal, or redundant-channel comparison.
The third limit is hollow-shaft mounting. The /20P bore must fit the prepared shaft without forcing, and the torque bracket must compensate shaft movement without creating bearing preload. Adapter-shaft radial eccentricity, axial movement, torque-arm binding, shaft shock, or poor link-head freedom can increase housing movement and appear as pulse jitter or reference instability.
Wiring & Installation
Before replacement, document both terminal-box connections separately. Record supply voltage, GND, shield connection, A/B/N signal sequence, inverted outputs, and any LED-check or diagnostic output used by the control system. Confirm that both counter inputs are scaled for 2000 PPR and that the system expects the same 0°/90° phase sequence and N marker behavior.
During mechanical installation, clean the customer shaft, centering surface, bolting faces, and fastening threads. Align the adapter shaft carefully, keep radial run-out within the application tolerance, avoid hammering the encoder, and make sure the hollow-shaft device is not pulled into position by force. The torque bracket should remain free at the link heads and should not transmit bending load into the bearings.
For signal stability, route non-inverted and inverted signals as paired conductors, keep feedback wiring away from inverter, motor, brake, contactor, and power cables, and maintain continuous shield bonding. After commissioning, verify pulse count, direction, N marker repeatability, redundant-channel agreement, shield continuity, and stable operation through the required speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed FGH 4 hollow-shaft and redundant terminal-box interface:
- Match 2000 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve KK dual terminal-box structure, N marker behavior, supply range, output level, and redundant-channel compatibility
- Adapt the FGH 4 /20P hollow-shaft bore, adapter-shaft fit, torque bracket position, sealing boundary, and cable-entry orientation
- Review 100 kHz / 150 kHz frequency margin, shielded twisted-pair routing, terminal-box mapping, bearing load, and redundant-channel agreement
Key Data
| Item | Data |
|---|---|
| Model | FGH4KK-2000G-90G-NG/20P |
| Encoder type | Incremental hollow-shaft encoder |
| Series | FGH 4 |
| Connection structure | KK, redundant dual terminal boxes |
| Pulses per revolution | 2000 PPR |
| Pulse disk class | Preferred glass-disk pulse rate |
| Signal output | Square wave, 0° and 90° channels |
| Inverted signals | Yes, Option G |
| Marker pulse | Option N with inverted marker signal |
| Hollow-shaft interface | /20P |
| Supply voltage | 12–30 VDC |
| Output type | Differential line-driver / push-pull style output |
| Frequency range | 0–100 kHz standard, up to 150 kHz if specified |
| Protection class | IP55 standard, IP56 versions depending on sealing and connection type |
| Mechanical checks | /20P bore fit, adapter-shaft run-out, torque bracket freedom, bearing load |
| Key replacement checks | 2000 PPR scaling, glass-disk edge stability, KK terminal-box mapping, A/B phase, N marker, shielding |
