A custom compatible replacement for FGH40KK-1024G-90G-NG/20P must preserve the 1024 PPR standard scaling, KK dual terminal-box layout, /20P hollow-shaft fit, A/B 90° phase relationship, inverted signal pairs, N reference pulse behavior, torque bracket freedom, adapter-shaft run-out, and EMC grounding. EncoderWorks can configure this replacement only when both terminal-box feedback paths remain electrically and mechanically consistent. The main failure boundary is a hollow-shaft system that runs normally on one channel but shows speed deviation, direction mismatch, reference-pulse error, or bearing stress when the redundant paths are compared. Typical production lead time: 15 working days.
This model belongs to the FGH 40 incremental hollow-shaft encoder platform. The 1024 PPR value is a standard pulse-rate configuration, so the replacement focus is stable reference scaling, redundant channel matching, A/B/N signal continuity, and controlled hollow-shaft mounting rather than special high-pulse operation. The KK structure should be treated as a two-terminal-box redundant layout, not as a plug-connected version or a single terminal-box configuration.
System Limits
The first system limit is 1024 PPR reference scaling. If one controller channel is configured for 1000, 1200, 2048, 4096, or another pulse count, both outputs may look electrically clean while speed, travel, and synchronization values become inconsistent. Edge-counting mode, gear ratio, direction logic, and speed conversion should be confirmed on both terminal-box paths.
The second limit is redundant terminal-box channel matching. Each terminal box must preserve A, /A, B, /B, N, and /N exactly as required by the controller or comparison system. If one phase pair is swapped, one inverted output is omitted, one shield reference is different, or the N reference pulse is wired differently between boxes, the machine may fail during homing, direction reversal, or redundant-channel comparison.
The third limit is hollow-shaft mechanical stability. The /20P interface must fit the prepared shaft without forcing, and the torque bracket must remain free at the link heads. Excessive adapter-shaft run-out, axial preload, radial load, shaft shock, or a bound torque arm can shorten bearing life and create pulse jitter or intermittent reference errors.
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 diagnostic output used by the control system. Confirm that both counter inputs are scaled for 1024 PPR and that both paths expect the same 0°/90° phase sequence and N reference pulse behavior.
During mechanical installation, clean the customer shaft, centering surface, bolting faces, and fastening threads. Align the adapter shaft carefully, avoid hammering the encoder, and make sure the hollow-shaft device is not pulled into position by force. The torque bracket should support housing reaction torque without creating bearing preload.
For EMC stability, use shielded signal cables, keep feedback wiring away from inverter, motor, brake, contactor, and power cables, and bond the grounding strap to a nearby low-impedance bare-metal grounding point. Cable glands and blanking plugs must be tightened properly, and cable strain must not pull sideways on the terminal-box entries. After commissioning, verify pulse count, direction, reference pulse, redundant-channel agreement, shielding continuity, and stable operation through the required speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed hollow-shaft and redundant terminal-box interface:
- Match 1024 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve KK dual terminal-box structure, N reference pulse behavior, supply range, output level, and redundant-channel compatibility
- Adapt the FGH 40 hollow-shaft /20P mounting interface, adapter-shaft fit, torque bracket position, sealing boundary, and cable-gland orientation
- Review 200 kHz counter margin, shielded wiring, terminal-box mapping, grounding strap, bearing load, and redundant-channel agreement
Key Data
| Item | Data |
|---|---|
| Model | FGH40KK-1024G-90G-NG/20P |
| Encoder type | Incremental hollow-shaft encoder |
| Series | FGH 40 |
| Connection structure | KK, two terminal boxes / redundant version |
| Pulses per revolution | 1024 PPR |
| Pulse-rate class | Standard pulse rate |
| Signal output | Square wave, 0° and 90° channels |
| Inverted signals | Yes, G output configuration |
| Reference pulse | NG, N reference pulse with inverted signal |
| Hollow-shaft interface | /20P |
| Supply voltage | 12–30 VDC |
| Output type | Current-limited, short-circuit-proof push-pull line driver |
| Maximum frequency | 200 kHz, higher on request |
| Protection class | IP65 standard, IP66 versions depending on sealing |
| Mechanical checks | /20P shaft fit, adapter-shaft run-out, torque bracket freedom, bearing load |
| Key replacement checks | 1024 PPR scaling, dual terminal-box channel matching, A/B phase, N reference pulse, EMC grounding |
