When replacing FG40K-2500G-90G-NG, EncoderWorks can configure a custom compatible replacement solution around the 2500 PPR scaling, A/B 90° phase relationship, inverted channels, NG reference pulse, radial terminal-box wiring, EMC cable-gland shielding, and coupling preload. The main failure boundary is a system that counts pulses correctly at first but calculates the wrong speed, loses reference repeatability, or becomes unstable under inverter noise after installation. Typical production lead time: 15 working days.
This configuration belongs to the FG 40 heavy-duty incremental encoder platform. It provides 2500 pulses per revolution with square-wave output, basic channel 0° A and pulse channel 90° B, inverted signal pairs, and a mechanically defined NG reference pulse with inverted signal. The K version should be treated as a radial single-terminal-box encoder, not as a KK dual-terminal-box or redundant wiring version. Replacement work should focus on pulse scaling, A/B phase accuracy, N pulse timing, output voltage level, terminal assignment, cable-gland sealing, shield bonding, and shaft coupling alignment.
System Limits
The first system limit is 2500 PPR counter scaling. If the controller is configured for 2000, 2048, 1000, 1024, or another pulse count, the speed and position conversion will be wrong even when the A/B signals look stable. Edge-counting mode, input frequency margin, speed display, travel calculation, and direction detection should be checked before startup.
The second limit is A/B/N signal behavior. The controller must receive A, /A, B, /B, N, and /N with the expected 90° phase displacement and repeatable reference-pulse timing. If the inverted channels, phase sequence, or N pulse wiring changes, the machine may run normally but fail during homing, zero return, synchronization, or direction reversal.
The third limit is radial terminal-box EMC and sealing. Loose cable glands, moisture entry, long shield drain wires, poor grounding, or cable routing near inverter and motor power wiring can create false edges. Coupling misalignment, axial preload, and radial load can also reduce bearing life and degrade signal stability.
Wiring & Installation
Before replacement, record the radial 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 cable diameter, gland sealing condition, shield contact method, grounding strap, and controller scaling for 2500 PPR.
During installation, align the coupling without force and do not strike the shaft or housing. Keep angular error, axial offset, and parallel displacement within the coupling tolerance used on the machine. Route signal and supply cables away from inverter output, motor lines, brakes, contactors, and solenoid valves. Tighten the cable gland and blanking plug, maintain shield continuity, and close the terminal-box cover without trapping the cable. After commissioning, verify pulse count, speed scaling, direction, N reference repeatability, terminal-box sealing, and signal stability over the full operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed drive and counter system:
- Match 2500 PPR square-wave incremental output with A/B 90° phase relationship and inverted channels
- Preserve NG reference pulse behavior, K radial terminal-box layout, supply voltage, output level, and counter input compatibility
- 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-box sealing, bearing load, and reference-pulse repeatability
Key Data
| Item | Data |
|---|---|
| Model | FG40K-2500G-90G-NG |
| Encoder type | Heavy-duty incremental encoder |
| Series | FG 40 |
| Connection structure | K radial terminal box |
| Pulses per revolution | 2500 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 | 2500 PPR scaling, A/B phase, NG reference pulse, terminal-box shielding, coupling preload |
