Configuring Yaskawa GA800 3-Wire Control: Wiring and Parameters

1. Overview: 3-Wire Control on the Yaskawa GA800

The Yaskawa GA800 is a high-performance industrial AC drive configured for either 2-wire (maintained) or 3-wire (momentary) control through parameter A1-03. 3-wire control is the conventional choice for machinery applications requiring a Normally Closed (NC) E-stop pushbutton, a Normally Open (NO) Start pushbutton, and a maintained-running latch. Unlike 2-wire control, where a maintained input directly drives the run state, 3-wire control uses momentary contacts and an internal latch, providing inherent fail-safe behavior on power-up.

On the GA800, the 3-wire macro is invoked by setting A1-03 = 3330. This preset automatically assigns default functions to the multi-function digital inputs (S1–S8) and configures the source/sink logic. Misapplication of the source/sink jumpers between SN, SP, and SC is the most common cause of nuisance faults and unresponsive run commands on this platform.

2. GA800 Control Terminal Architecture

The GA800 control board exposes the following low-voltage terminals relevant to run/stop wiring:

The internal 24 VDC rail between SN (–) and SP (+) provides power to the digital inputs and to external sensors. SC is the return path; it is electrically isolated from SN and is the reference for whichever logic polarity is selected.

2.1 Source/Sink (PNP/NPN) Selection

The GA800 supports both PNP (source) and NPN (sink) digital input logic via a single jumper between SC and either SN or SP:

For most North American panels using 3-wire pushbuttons with dry contacts, PNP (SN–SC jumper) is preferred because the pushbutton contacts switch the +24 V to S1/S5/S6, and a wire break will fail-safe to OFF.

3. 2-Wire vs 3-Wire Control Theory

3.1 2-Wire (Maintained) Control — A1-03 = 2220

In 2-wire mode, a maintained contact closure is required to keep the drive in the run state. This is typical for applications where a selector switch, HOA (Hand-Off-Auto) contact, or PLC output directly commands run. On power-up, the drive will run immediately if the run input is closed at the moment of initialization unless parameter b1-11 (Run Command Delay on Power-Up) is enabled to delay or ignore the input.

3.2 3-Wire (Momentary) Control — A1-03 = 3330

In 3-wire mode, the GA800 implements an internal seal-in circuit:

1. NC Stop input (S1): A Normally Closed contact must be held closed. Opening S1, even momentarily, drops the run latch and commands a stop (per the configured stopping method in b1-03).
2. NO Forward Run input (S5): A momentary closure to the active logic level sets the run latch and commands forward rotation. S5 defaults to function value 0 = Forward Run Command (3-wire).
3. NO Reverse Run input (S6): A momentary closure commands reverse rotation. S6 defaults to function value 1 = Reverse Run Command (3-wire).

The latch is reset by any of: opening S1, a fault condition, an STO event, or a stop command via keypad/serial.

4. A1-03 Application Preset Macros

Parameter A1-03 is the GA800's Application Preset. It writes a coordinated set of values to multiple parameters in a single operation. The most common presets are:

5. H1 Digital Input Function Assignments

After A1-03 = 3330 is set, verify the digital input functions via the H1 parameter group. H1-01 maps to terminal S1, H1-02 to S2, and so on through H1-08 mapping to S8.

Function value 0 on H1-05 in 3-wire mode is the Forward Run Command. In 2-wire mode (A1-03=2220), the same value 0 on H1-01 is Forward Run Maintained — confirming why source/sink polarity errors look identical to "wrong preset" faults during commissioning.

6. Prerequisites for 3-Wire Conversion

• Drive firmware version: GA800 firmware PRG: 01012 or later (verify under U1-14); older firmware required manual H1-x assignment.
• Quick Setup Procedure foldout (shipped with drive) for the Safe Disable / STO jumper position.
• DriveWizard Industrial (Yaskawa, free download) or keypad access to verify U1-xx monitor group post-configuration.
• Multimeter capable of 24 VDC measurement on the control terminal strip.
• Verify drive is in STOP state and main input power is locked out per local arc-flash / lockout-tagout procedure before moving the source/sink jumper.

7. Step-by-Step: Wiring a GA800 in 3-Wire Mode

1. Lock out and tag out the upstream disconnect. Verify zero energy at the drive input terminals L1/L2/L3 with a properly rated tester.
2. Select source/sink logic. Place the jumper between SN and SC for PNP (recommended for dry-contact pushbuttons). Place between SP and SC for NPN. Do NOT place between SN and SP.
3. Configure the STO jumper. If the Safe Disable inputs (H1, H2) are not used, install the supplied STO jumper between H1–HC and H2–HC. Removing this jumper while the drive is powered will drop output to the motor instantly (b1-29 controlled).
4. Wire the NC Stop pushbutton from SN (PNP) to S1. Wire the NO Start pushbutton from SN (PNP) to S5. Wire the NO Reverse pushbutton from SN (PNP) to S6. All three return through the same +24 V bus.
5. Power up the drive and enter A1-03 = 3330 on the keypad. Confirm with the Enter key; the drive will display "Initialization" for ~5 seconds.
6. Verify H1 group. Navigate to H1-01 → H1-08 and confirm the assignments shown in Section 5.
7. Set b1-03 (Stopping Method) to match the application: 0 = Ramp to Stop, 1 = Coast to Stop, 2 = DC Injection Braking, 3 = Ramp with timer.
8. Set b1-11 (Run Command at Power-Up) to 0 = Ignore Existing Run Command. This is critical: it forces the operator to re-push Start after power-up or after switching from Local to Remote, preventing an unexpected start.
9. Set b1-14 (Reverse Select) to 0 = Reverse Enabled, or 1 = Reverse Disabled if reverse rotation is mechanically prohibited (e.g., extruder, unidirectional pump).

8. Safe Torque Off (STO) Behavior in 3-Wire Mode

The GA800 implements STO per IEC 61800-5-2 SIL3 / PLe via dual-channel inputs H1 and H2. When STO is engaged (both channels dropped), the output transistors are forced off within ≤20 ms and the drive displays bb (baseblock) or Sto alarm depending on configuration.

Critical interaction with 3-wire run state:

1. E-stop hit → STO engaged → drive baseblocks.
2. E-stop reset → STO released → drive remains stopped.
3. If the run input (S5 or S6) is STILL closed when STO releases, the GA800's Run LED will flash (typically 0.5 Hz) to indicate "run command present but not executing."
4. Operator must cycle Stop (open S1) and re-push Start to re-engage.

9. Verification and Commissioning

10. Troubleshooting Matrix

11. Common Pitfalls and Field Notes

• Presetting overwrites user parameters. A1-03 = 3330 wipes the motor autotune results (T1 group) in some firmware revisions. Always run Rotational Auto-Tune (T1-01 = 2) AFTER setting A1-03.
• Analog reference vs digital reference. After 3-wire conversion, verify b1-01 (Reference Source) remains at the expected value; the macro does not change it.
• Multi-function input debounce. H1-12 (DI Scan Time) defaults to 1 = 4 ms. For mechanically noisy environments, increase to 2 (8 ms) or 3 (16 ms) to suppress bounce-induced double-starts.
• M1/M2 relay as holding contact. A common alternative to true 3-wire is to wire the start/stop series chain to S1 in 2-wire mode, then use M1/M2 (Drive Running) as a seal-in across the Start PB. This emulates 3-wire behavior with one extra relay contact. It is acceptable but is not true 3-wire logic and bypasses the run-edge detection.
• Local/Remote transition. Parameter b1-07 (LOC/REM Run Select) determines whether switching from Local to Remote with a run command present will start the drive. Default is 0 = Cycle Run Required, which forces re-start after source change — preferred for safety.
• EMC. Route 24 V control wiring in a separate conduit from motor power (U/T1, V/T2, W/T3). Use shielded twisted pair for any control runs exceeding 3 m.

12. Document References

Authoritative documentation for the GA800, including the Quick Setup foldout shipped with every unit and the full Product Instructions manual (document number TOEPYAIGA8001), is published on the official Yaskawa product page at GA800 AC Drive Product Instructions. For conceptual background on 2-wire vs 3-wire control definitions, refer to Yaskawa's published drive-control FAQ at Yaskawa Drive Knowledge Base. Always cross-check parameter numbers and default values against the revision of the manual corresponding to the firmware reported in U1-14 / U1-15.