Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
The Yaskawa A1000 is one of the most capable mid-range AC drives available — a full-featured vector-control drive that handles everything from simple V/f applications to full closed-loop flux vector control with encoder feedback. Its fault code system is comprehensive and well-documented, making diagnosis straightforward when you know how to use the drive’s built-in diagnostics. This guide covers the complete fault code reference, the key parameters you need to know, and a step-by-step commissioning procedure.
What Does Yaskawa A1000 Fault Data Mean?
The A1000 displays fault codes on its digital operator (keypad). Navigate to the fault history via U2-01 (current fault) and U2-02 through U2-10 (fault history). Each fault entry also logs the output frequency, current, voltage, and drive status at the time of fault.
Overcurrent and Short Circuit Faults
| Code | Name | Common Cause |
|---|---|---|
| OC | Overcurrent | Acceleration too fast, motor short, mechanical jam |
| SCA | Overcurrent (during stop) | Output short circuit, IGBT failure |
| GF | Ground Fault | Motor winding or cable insulation failure |
| SC | Short Circuit | Direct output phase short |
| OCA | Overcurrent (during acceleration) | Ramp time too short |
| OCD | Overcurrent (during deceleration) | Load regeneration exceeding DC bus capacity |
| OCR | Overcurrent (during constant speed) | Sudden load spike, mechanical fault |
Overvoltage and Undervoltage
| Code | Name | Common Cause |
|---|---|---|
| OV | DC Bus Overvoltage | Fast deceleration, regenerative load, high input voltage |
| UV1 | DC Bus Undervoltage | Low input voltage, power dip, blown input fuse |
| UV2 | Control Power Undervoltage | Internal control supply failure |
| UV3 | Soft Charge Circuit Fault | Pre-charge relay not closing |
| PF | Input Phase Loss | Missing input phase, blown fuse |
Motor and Thermal Faults
| Code | Name | Common Cause |
|---|---|---|
| oL1 | Motor Overload (electronic thermal) | Motor running above rated load continuously |
| oL2 | Drive Overload | Drive running above rated current continuously |
| oH1 | Drive Overheat | Insufficient cooling, blocked heatsink |
| oH2 | Motor Overheat (thermistor) | Motor PTC/NTC thermistor tripped |
| OH3 | Motor Overheat (oL1 pre-alarm) | Motor approaching thermal limit |
Communication and Encoder Faults
| Code | Name | Common Cause |
|---|---|---|
| bUS | Communication Error | MEMOBUS/Modbus timeout, loose RS-485 wiring |
| CE | MEMOBUS/Modbus Communication Error | PLC stopped communicating, wiring fault |
| EF0 | External Fault (terminal S1) | External safety circuit opened |
| EF1–EF8 | External Fault (terminals S1–S8) | External fault input activated |
| dEv | Speed Deviation | Encoder fault, mechanical slip in closed-loop mode |
| PGo | Encoder Open Circuit | Encoder cable disconnected or broken |
Safety and Other Faults
| Code | Name | Common Cause |
|---|---|---|
| SEr | EEPROM Write Error | Parameter save failure |
| CPF00 | EEPROM Error | Control board fault |
| CPF02 | A/D Converter Fault | Control board fault |
| Err | EEPROM Error | Corrupted parameter memory |
| STP | Safety Circuit Fault | Safe Torque Off (STO) circuit open |
| LF | Output Phase Loss | Missing motor phase, blown motor lead |
Key Parameters
Understanding these parameter groups is essential for A1000 commissioning and fault diagnosis.
Motor Setup (Parameter Group E)
| Parameter | Function | Typical Setting |
|---|---|---|
| E1-01 | Input voltage (V) | Match supply voltage |
| E2-01 | Motor rated current (A) | Motor nameplate FLA |
| E2-02 | Motor rated slip (Hz) | Calculate from nameplate |
| E2-03 | Motor no-load current (A) | Typically 30–50% of E2-01 |
| E2-04 | Motor poles | 4 for 1800 RPM, 6 for 1200 RPM |
| E2-05 | Motor rated power factor | Motor nameplate cos φ |
Acceleration and Deceleration (Parameter Group C)
| Parameter | Function |
|---|---|
| C1-01 | Acceleration Time 1 (seconds) |
| C1-02 | Deceleration Time 1 (seconds) |
| C1-03 | Acceleration Time 2 |
| C1-04 | Deceleration Time 2 |
| C6-01 | Drive duty cycle (Heavy Duty vs. Normal Duty) |
Protection Parameters (Parameter Group L)
| Parameter | Function |
|---|---|
| L1-01 | Motor protection selection (electronic thermal) |
| L1-02 | Motor overload protection time constant |
| L2-01 | Momentary power loss ride-through enable |
| L3-01 | Acceleration stall prevention enable |
| L3-02 | Deceleration stall prevention enable |
| L5-01 | Number of auto restart attempts |
| L5-02 | Auto restart fault list |
Reference and Speed Control (Parameter Group d)
| Parameter | Function |
|---|---|
| d1-01 | Frequency reference 1 |
| d1-17 | Jog frequency |
| d2-01 | Frequency reference upper limit |
| d2-02 | Frequency reference lower limit |
How to Fix It
Step 1: Pre-Power Inspection
Before applying power:
- Verify input voltage matches drive nameplate (200V class or 400V class).
- Verify motor voltage matches the selected V/f pattern.
- Verify output cable connections at U, V, W terminals and motor terminal box — check phase rotation if motor direction matters.
- Verify grounding: drive PE terminal to building ground, motor frame to drive PE.
- Check that all terminal screws are torqued to spec (see hardware manual for terminal torque specs).
- Verify no output cable is connected to input terminals.
Step 2: Initial Power-Up and Parameter Initialization
- Apply power to the A1000. The digital operator displays “HAND OFF AUTO” or the frequency reference.
- If starting fresh, initialize to factory defaults: A1-03 = 2220 (2-wire initialization) or A1-03 = 3330 (3-wire initialization). Press ENTER and confirm.
- Set the control mode: A1-02 = 0 (V/f), 1 (V/f with encoder), 2 (Open-loop vector), 3 (Closed-loop vector), 5 (Open-loop vector 2).
Step 3: Enter Motor Nameplate Data
Navigate to parameter group E2 and enter:
- E2-01: Motor rated current (A) — from nameplate “FLA” or “A”
- E2-04: Number of motor poles — 2 for 3600 RPM, 4 for 1800 RPM, 6 for 1200 RPM
- E2-05: Motor rated power factor
- E1-01: Input voltage
- E1-03: V/f pattern selection (01 = 60 Hz, 00 = 50 Hz, or custom)
Step 4: Run Auto-Tuning
For Open-Loop Vector (A1-02 = 2) or Closed-Loop Vector (A1-02 = 3) modes, run rotational auto-tuning:
- T1-01 = 0 (Rotational Auto-Tuning) — requires motor to be uncoupled from load
- T1-02 = Motor rated power (kW)
- T1-03 = Motor rated voltage
- T1-04 = Motor rated frequency (Hz)
- T1-05 = Motor rated speed (RPM)
- T1-06 = Motor rated current (A)
- T1-07 = Motor poles
Press RUN on the digital operator to start auto-tuning. The motor rotates slowly during this process. Auto-tuning takes 30–90 seconds and writes measured values back to E2 parameters.
For applications where load cannot be disconnected, use T1-01 = 2 (Stationary Auto-Tuning) which measures resistance and inductance without rotating the motor.
Step 5: Set Acceleration/Deceleration Times
- C1-01: Acceleration time 1 — start at 10 seconds for general loads, increase for high-inertia loads.
- C1-02: Deceleration time 1 — for drives without a braking resistor, set to the minimum time that doesn’t trigger OV fault.
- Enable deceleration stall prevention (L3-04 = 1) if OV faults occur during deceleration.
Step 6: Configure Speed Reference
- b1-01 = 1: Frequency reference from analog input (0–10V or 4–20mA at terminal A1 or A2).
- b1-01 = 0: Frequency reference from digital operator.
- b1-02: Run command source (1 = digital input terminals, 0 = digital operator).
Step 7: Configure Motor Protection
- L1-01 = 1: Enable electronic thermal protection.
- L1-02: Set overload time constant — typically 9 minutes for standard motors, 2 minutes for inverter-duty motors with forced cooling.
Step 8: Test Run
- Start with a low frequency reference (10–15 Hz) and verify motor rotation direction.
- If direction is wrong, swap any two output terminals (U↔V or V↔W) at the drive or motor.
- Increase to full speed and monitor output current in monitor U1-03. Compare to motor nameplate FLA.
- Monitor heatsink temperature in U4-06 during extended operation.
Parts You May Need
| Part | Use | Amazon Link |
|---|---|---|
| Yaskawa A1000 Digital Operator (JOG) | Replace failed keypad / display | |
| Megohmmeter Insulation Tester | Test motor windings before commissioning | |
| Yaskawa A1000 Braking Resistor | Prevent OV faults on regenerative loads | |
| RS-485 to USB Converter Cable | Connect A1000 to PC for DriveWizard | |
| Shielded Control Cable (18 AWG) | Reduce noise on analog reference inputs |
Need replacement parts? Search for parts and tools on Amazon.
When to Call a Pro
- CPF faults (control board errors): CPF00, CPF02, CPF20 indicate control board hardware failure. Send the drive to a Yaskawa repair center.
- OC at startup with known good motor: If insulation tests pass and OC persists, the drive’s IGBT module may have failed. Requires power module replacement.
- Encoder (PGo, dEv) faults in closed-loop mode: Closed-loop vector commissioning requires careful encoder wiring and parameter tuning. Contact Yaskawa application engineering for complex applications.
FAQ
Q: What’s the difference between OC and OCA on the Yaskawa A1000?
A: OCA is “Overcurrent during Acceleration” — the drive detected overcurrent specifically while the output frequency was ramping up. This helps you pinpoint the cause: the acceleration ramp time is too short for the load inertia. Increase C1-01. OC without a suffix means overcurrent occurred during constant speed operation, pointing to a sudden load spike or mechanical fault.
Q: How do I clear a fault on the Yaskawa A1000?
A: Press the RESET key on the digital operator after addressing the root cause. Alternatively, close and open a digital input configured as fault reset (H1-xx = 14). Via Modbus, write bit 4 of the command word to clear faults.
Q: My A1000 shows UV1 on power-up, but the supply voltage is correct. What’s wrong?
A: UV1 that clears after a few seconds is often normal — the DC bus charging through the pre-charge resistors takes a moment to reach operating voltage. If UV1 persists or appears randomly during operation, check: input fuse condition, input line voltage under load (not just at the panel), and pre-charge relay operation (UV3 would indicate pre-charge circuit specifically).
Q: How long is the Yaskawa A1000 warranty?
A: Standard Yaskawa A1000 warranty is 2 years from date of manufacture (not date of installation). Extended warranty options are available through Yaskawa distributors. Register your drive at Yaskawa’s website to activate and track warranty coverage.
Technician Tips
Yaskawa VFD faults display as two-letter codes on the LED operator: oC (overcurrent), ov (overvoltage), GF (ground fault), oH (overtemperature). The fault history is accessed through the operator diagnostic menu — record the fault code and the drive state (running, accelerating, decelerating, stopped) before clearing. On V1000 drives, Uv1 (DC bus undervoltage) that appears during high line power conditions suggests main capacitor degradation. GA700 drives have a built-in fan speed monitor — check parameter o4-03 for actual fan speed in RPM.
Prevention: Schedule annual heatsink cleaning with compressed air. A blocked heatsink is the #1 cause of oH faults on Yaskawa drives operating in industrial environments.