FG40KK-1200G-90G-NG should be matched as a 1200 PPR dual-terminal-box incremental encoder, where EncoderWorks can configure a custom compatible replacement solution only if the A/B 90° phase relationship, inverted channels, NG reference pulse, KK wiring layout, counter input margin, EMC grounding, and coupling preload remain unchanged. The main failure boundary is a machine that still counts pulses but loses direction stability, reference repeatability, or clean signal separation after replacement. Typical production lead time: 15 working days.
This configuration belongs to the FG 40 heavy-duty incremental encoder platform. It uses 1200 pulses per revolution with square-wave output, basic channel 0° A and pulse channel 90° B, inverted signals, and a mechanically defined NG reference pulse with inverted signal. The KK structure should be treated as a dual terminal-box or redundant-style wiring arrangement, not as a single terminal-box K version. Replacement work should focus on pulse rate, A/B phase accuracy, N reference timing, output voltage level, counter input compatibility, shield termination, cable routing, and mechanical coupling alignment.
System Limits
The first system limit is counter compatibility. A 1200 PPR encoder changes the pulse count per mechanical revolution compared with 1024 PPR versions, so the controller scaling, speed calculation, edge-counting mode, and maximum input frequency must be checked. If the counter configuration remains set for another pulse rate, speed or position values can be wrong even when the electrical signals are stable.
The second limit is A/B/N signal integrity. The controller must receive A, /A, B, /B, N, and /N with the expected 90° phase displacement and reference-pulse behavior. If the inverted channels, phase displacement, or N pulse timing changes, the system may run normally but fail during direction reversal, homing, or zero confirmation.
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, redundant wiring, or cabinet-side service access.
Wiring & Installation
Before replacement, record the terminal-box wiring for A, /A, B, /B, N, /N, supply voltage, GND, shield, and any diagnostic or error output used by the machine. Confirm whether both KK terminal boxes are used for redundancy, signal separation, cabinet routing, or service isolation.
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, controller scaling, terminal-box wiring separation, and signal stability across the operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed drive and counter system:
- Match 1200 PPR square-wave incremental output with A/B 90° phase relationship and inverted channels
- Preserve NG reference pulse behavior, KK dual-terminal-box layout, supply voltage, output level, and counter input compatibility
- Adapt the FG 40 mechanical envelope, flange or foot mounting requirement, shaft interface, coupling alignment, and cable-gland layout
- Review counter scaling, shield grounding, EMC routing, terminal separation, bearing load, and reference-pulse repeatability
Key Data
| Item | Data |
|---|---|
| Model | FG40KK-1200G-90G-NG |
| Encoder type | Heavy-duty incremental encoder |
| Series | FG 40 |
| Connection structure | KK dual terminal box / redundant-style version |
| Pulses per revolution | 1200 PPR |
| Pulse category | Standard pulse rate |
| Signal output | Square wave A/B, 90° phase |
| Inverted signals | Yes |
| Reference pulse | NG, with inverted signal |
| 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 reference pulse, terminal-box wiring, EMC grounding |
