FG40KK-1000G-90G-NG-S should be specified as a 1000 PPR feedback and overspeed-monitoring encoder, where EncoderWorks can configure a custom compatible replacement solution only if the A/B 90° phase relationship, inverted channels, NG reference pulse, Option S switching behavior, KK dual-terminal-box wiring, counter scaling, EMC grounding, and coupling preload remain unchanged. The main failure boundary is a replacement that counts normally but changes speed calculation, reference repeatability, overspeed trip behavior, or terminal-box separation. Typical production lead time: 15 working days.
This configuration belongs to the FG 40 heavy-duty incremental encoder platform. It uses 1000 pulses per revolution with square-wave output, basic channel 0° A and pulse channel 90° B, inverted signals, a mechanically defined NG reference pulse with inverted signal, and Option S electronic overspeed switching. The KK structure should be treated as a dual terminal-box or redundant-style arrangement, especially where the installed machine separates feedback, reference, diagnostics, or overspeed wiring. Replacement work should focus on pulse rate, A/B phase accuracy, N reference timing, overspeed switching thresholds, output voltage level, counter input compatibility, shield termination, and mechanical coupling alignment.
System Limits
The first system limit is 1000 PPR counter scaling. This pulse count changes the speed and position conversion compared with 1024, 2048, 2500, or high-pulse versions. If the controller scaling, edge-counting mode, or speed calculation remains configured for another pulse rate, the encoder may produce clean signals while the machine displays the wrong speed or travel value.
The second limit is Option S overspeed behavior. The overspeed function must be checked as part of the machine protection chain, not as a secondary output. Switching thresholds, output state, terminal assignment, response behavior, and reset logic must match the installed drive or protection circuit. If A/B feedback remains correct but the overspeed output changes, the machine can lose a speed-protection boundary.
The third limit is mechanical and EMC installation. Coupling misalignment, axial preload, radial load, weak shield bonding, or signal wiring routed near inverter and motor cables can degrade edge quality and shorten bearing life. The KK dual terminal-box layout must also be preserved if the machine uses separated signal paths or service-isolated wiring.
Wiring & Installation
Before replacement, record the terminal-box wiring for A, /A, B, /B, N, /N, supply voltage, GND, shield, error output if used, and Option S switching outputs. Confirm how the two terminal boxes are used: redundant feedback, separated cabinet routing, overspeed output, diagnostics, or maintenance access.
During installation, align the coupling without force and do not hammer the shaft or housing. Keep angular error, axial offset, and parallel displacement within the coupling tolerance used on the machine. Route signal and supply wiring away from inverter, motor, brake, contactor, and solenoid cables. Use low-impedance grounding, maintain shield continuity, and seal the terminal boxes and cable glands before startup. After commissioning, verify pulse count, direction, N reference repeatability, overspeed switch response, counter scaling, terminal-box separation, and signal stability across the operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed counter and overspeed system:
- Match 1000 PPR square-wave incremental output with A/B 90° phase relationship and inverted channels
- Preserve NG reference pulse behavior, Option S overspeed switching, KK dual-terminal-box layout, supply voltage, and output level
- Adapt the FG 40 mechanical envelope, shaft interface, flange or foot mounting requirement, coupling alignment, and cable-gland layout
- Review counter scaling, shield grounding, EMC routing, terminal separation, bearing load, reference repeatability, and protection logic
Key Data
| Item | Data |
|---|---|
| Model | FG40KK-1000G-90G-NG-S |
| Encoder type | Heavy-duty incremental encoder |
| Series | FG 40 |
| Connection structure | KK dual terminal box / redundant-style version |
| Pulses per revolution | 1000 PPR |
| Pulse category | Standard pulse rate |
| Signal output | Square wave A/B, 90° phase |
| Inverted signals | Yes |
| Reference pulse | NG, with inverted signal |
| Option | S electronic overspeed switch |
| Supply voltage | 12–30 VDC |
| Output type | Push-pull line driver |
| Max frequency | 200 kHz |
| Standard shaft | 11j6 × 30 mm |
| Optional shaft | 14j6 × 30 mm |
| Key checks | Counter scaling, A/B phase, N pulse, overspeed switch, terminal-box wiring, EMC grounding |
