FG4KK-5000G-90G-NG should be treated as a redundant glass-disk FG 4 feedback encoder, where EncoderWorks can configure a custom compatible replacement solution around the 5000 PPR scaling, KK dual-terminal-box structure, duplicated scanning outputs, A/B 90° phase relationship, inverted signal pairs, N marker behavior, shielded twisted-pair routing, and coupling preload. The main failure boundary is a redundant feedback loop that works on one channel but develops counter mismatch, direction disagreement, or marker inconsistency when both terminal boxes are compared under speed and EMC stress. Typical production lead time: 15 working days.
This configuration belongs to the FG 4 optical incremental encoder platform for heavy-duty industrial environments. The 5000 PPR value belongs to the preferred glass-disk pulse-rate group, so the replacement must preserve both the high-resolution pulse behavior and the redundant KK wiring structure. The KK version should not be handled as a single K terminal-box encoder. It uses two terminal boxes and two scanning/evaluation systems, so both signal paths must be checked separately for terminal assignment, shield bonding, supply integrity, controller input compatibility, and marker-pulse behavior.
System Limits
The first system limit is 5000 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 5000 PPR, the usable shaft speed must be checked against the counter bandwidth, edge-counting mode, acceleration profile, and any redundant comparison logic. A channel may look stable at low speed but lose agreement during braking, reversal, or full-load operation.
The second limit is redundant channel consistency. Each KK terminal box must preserve the same A, /A, B, /B, N, and /N logic expected by the machine. If one channel has a swapped phase pair, different shield condition, or different marker interpretation, the controller may report speed deviation, direction mismatch, or zero-reference disagreement.
The third limit is EMC and mechanical stability. A-/A, B-/B, and N-/N should be routed as paired shielded conductors. Long exposed shield drains, loose cable glands, moisture inside either terminal box, inverter-side cable routing, coupling preload, shaft runout, or radial load can create edge jitter that becomes visible in redundant comparison.
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 both channels are read by one drive, two independent counters, or a safety comparison circuit.
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 maximum operating speed.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed redundant feedback system:
- Match 5000 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-5000G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | KK redundant dual terminal boxes |
| Pulses per revolution | 5000 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 | 5000 PPR counter margin, KK channel agreement, N marker behavior, terminal-box shielding, coupling preload |
