For FGH4K-2828G-90G-NG/20P, EncoderWorks can configure a custom compatible replacement solution only if the 2828 PPR special pulse-rate scaling, K single terminal-box wiring, /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 machine that receives pulses but calculates the wrong speed, loses direction logic, misses the reference position, or develops bearing stress because the custom pulse count, terminal assignment, bore fit, or torque-arm condition has changed. Typical production lead time: 15 working days.
This model belongs to the FGH 4 hollow-shaft incremental encoder platform. The 2828 PPR value should be treated as a special pulse-rate request, not as a standard preferred pulse value. Replacement work should therefore confirm the exact installed resolution, counter scaling, edge-counting mode, A/B phase sequence, N marker interpretation, and terminal-box pin assignment before production. The K version is a single terminal-box configuration, so it should not be written or installed as a KK redundant dual-terminal-box version.
System Limits
The first system limit is 2828 PPR custom scaling. If the controller is configured for 2000, 2048, 3000, 4096, or another nearby value, the encoder may output stable square waves while speed, travel, and synchronization values are wrong. Gear ratio, edge-counting mode, direction logic, and machine conversion factors must be checked against the actual 2828 PPR value.
The second limit is K terminal-box signal assignment. The terminal box must preserve A, /A, B, /B, N, and /N exactly as expected by the controller. If one inverted signal is omitted, one phase pair is swapped, or the N marker is assigned to a different terminal, the machine may run but fail during homing, zero return, or direction reversal.
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 loading the bearings. Adapter-shaft radial eccentricity, axial movement, torque-arm binding, shaft shock, or poor link-head freedom can create pulse jitter and reference instability, especially when the controller expects a non-standard pulse count.
Wiring & Installation
Before replacement, record the terminal-box connection for supply voltage, GND, shield, A/B/N signal sequence, inverted outputs, and any LED-check or diagnostic output used by the control system. Confirm that the counter input is scaled for 2828 PPR and that the application 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, avoid hammering the encoder, and do not pull the hollow-shaft device 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, shield continuity, terminal-box sealing, and stable operation through the required speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed FGH 4 hollow-shaft and terminal-box interface:
- Match 2828 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve K single terminal-box structure, N marker behavior, supply range, output level, and controller input 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 custom pulse-rate confirmation
Key Data
| Item | Data |
|---|---|
| Model | FGH4K-2828G-90G-NG/20P |
| Encoder type | Incremental hollow-shaft encoder |
| Series | FGH 4 |
| Connection structure | K single terminal box |
| Pulses per revolution | 2828 PPR |
| Pulse disk class | Special pulse rate on request |
| 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 | 2828 PPR confirmation, terminal-box mapping, A/B phase, N marker, shielding, counter scaling |
