FG4KK-8192G-90G-NG is a high-resolution redundant FG 4 feedback encoder, where EncoderWorks can configure a custom compatible replacement solution only if the 8192 PPR glass-disk scaling, KK dual-terminal-box structure, duplicated scanning systems, A/B 90° phase relationship, inverted signal pairs, N marker behavior, shielded twisted-pair routing, and coupling preload are preserved as one matched feedback system. The main failure boundary is a machine that counts correctly on one channel but develops speed deviation, direction disagreement, or marker-position mismatch when both redundant outputs are compared at operating speed. Typical production lead time: 15 working days.
This configuration belongs to the FG 4 optical incremental encoder platform for heavy-duty industrial environments. The 8192 PPR value is a preferred glass-disk pulse rate, so the replacement must be treated as a high-resolution counter-frequency and signal-integrity case, not only as a terminal-box wiring task. The KK version uses two terminal boxes and two scanning/evaluation systems, not a single K layout. Both signal paths must be checked separately for terminal assignment, shield bonding, supply integrity, controller input compatibility, phase sequence, and marker-pulse interpretation.
System Limits
The first system limit is 8192 PPR counter-frequency margin. FG 4 square-wave output is normally defined around a 0–100 kHz frequency range, with 150 kHz only when specified. At 8192 PPR, usable shaft speed must be checked against the counter bandwidth, selected edge-counting mode, acceleration profile, and any redundant comparison logic. A channel that is stable at low speed can lose agreement during reversal, braking, or full-load operation.
The second limit is redundant A/B/N consistency. Each KK terminal box must preserve the expected A, /A, B, /B, N, and /N relationship. If one phase pair is swapped, one inverted signal is omitted, or one marker input is interpreted differently, the controller may detect speed deviation, direction mismatch, homing error, or zero-reference disagreement.
The third limit is glass-disk signal stability under mechanical and EMC stress. At 8192 PPR, small shaft runout, coupling preload, vibration, loose cable glands, long exposed shield drains, moisture inside either terminal box, or inverter-side cable routing can appear as edge jitter. A-/A, B-/B, and N-/N should be routed as paired shielded conductors on both redundant channels.
Wiring & Installation
Before replacement, document both KK terminal boxes separately. Record the basic channel, 90° channel, marker pulse, inverted signals, supply voltage, GND, shield connection, LED-check or diagnostic output if used, and the controller or safety input connected to each system. Confirm whether the two channels are read by one drive, two independent counters, or a safety comparison circuit, and verify the 8192 PPR scaling on both paths.
During installation, fit the coupling smoothly and do not strike the shaft or housing. Keep the encoder centered, control angular and parallel offset, and avoid axial preload. Route both sets of A-/A, B-/B, and N-/N through shielded twisted pairs, keep the cable away from inverter output, motor, brake, and contactor wiring, and maintain terminal-box sealing on both sides. After commissioning, verify pulse count, speed scaling, direction, N marker behavior, redundant-channel agreement, terminal-box sealing, and signal stability at the highest operating speed.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed redundant feedback system:
- Match 8192 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve KK dual-terminal-box structure, redundant channel separation, N marker behavior, supply range, and output level
- Adapt the FG 4 mechanical envelope, shaft interface, flange or foot mounting requirement, coupling alignment, and cable-gland layout
- Review 100 kHz / 150 kHz frequency margin, shielded twisted-pair routing, EMC grounding, terminal-box sealing, bearing load, and redundant-channel agreement
Key Data
| Item | Data |
|---|---|
| Model | FG4KK-8192G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | KK redundant dual terminal boxes |
| Pulses per revolution | 8192 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 |
| Redundant structure | Two scanning/evaluation systems |
| 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 |
| Standard shaft | Ø11j6 × 30 mm |
| Optional shaft | Ø14j6 × 30 mm |
| Key checks | 8192 PPR counter margin, glass-disk stability, KK channel agreement, N marker behavior, dual terminal-box shielding |
