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ocA Over-Current during Acceleration fault in delta drive troubleshooting Description The ocA fault indicates that the output current of the Variable Frequency Drive (VFD) has exceeded the rated current limit (typically 200% to 300% depending on the model) specifically during the acceleration ramp-up phase. This implies that as the drive attempts to increase the frequency to speed up the motor, the load or a system defect is drawing excessive amperage instantaneously. Causes The primary causes for an ocA fault generally fall into three categories: parameter settings, mechanical load, or electrical shorts. 1. Acceleration Time too Short: If the acceleration time (Parameter 01-09 or similar) is set too low, the drive attempts to overcome the inertia of the motor and load too quickly, requiring massive current. 2. Short Circuit or Ground Fault: There may be a p...

ocd Over-Current during Deceleration fault in delta drive troubleshooting Description The ocd fault signifies that the output current exceeded the drive’s safety threshold while the motor was slowing down (decelerating). This differs from acceleration faults because it is often linked to regeneration energy and the drive fighting against the motor's kinetic energy to bring it to a stop. Causes When a motor is forced to stop faster than it naturally would (coasting), it acts as a generator. However, an Over-Current during this phase usually means the drive is trying to impose a frequency change that results in a high current slip. 1. Deceleration Time too Short: The drive is trying to force the motor to zero speed too aggressively. 2. External Force: A load (like a fan in a draft or a downhill conveyor) is driving the motor faster than the VFD frequency...

ocn Over-Current during Constant Speed fault in delta drive troubleshooting Description The ocn fault occurs when the drive detects an over-current condition while the motor is running at a steady, constant speed. This is arguably the most problematic of the OC faults because the system is supposed to be in a stable state, implying a sudden change in conditions. Causes Sudden spikes in current during steady operations are usually external: 1. Sudden Load Change: A jam in a conveyor, a sudden blockage in a pump, or a mechanical binding in a gearbox can instantly spike torque demand and current. 2. Insulation Breakdown: As the motor heats up during operation, weak insulation might fail, causing an intermittent arc/short that triggers the protection. 3. Loose Wiring: Vibrations at constant speed might cause a loose connection to arc, creatin...

ovA Over-Voltage during Acceleration fault in delta drive troubleshooting Description ovA indicates that the DC bus voltage inside the VFD has exceeded its maximum limit (e.g., 410V for 220V class, 820V for 440V class) while the drive was accelerating. This is a less common fault than over-current during acceleration but points to specific power supply issues. Causes 1. Input Voltage Surge: The mains power supply might have spiked. If using a capacitor bank for power factor correction on the main grid, switching it on can cause voltage swells. 2. Restarting a Spinning Motor: If the VFD attempts to accelerate a motor that is already spinning (windmilling fan), the back EMF generated by the motor can sum with the drive voltage, causing a DC bus spike. 3. Peripheral Hardware: Incorrectly wired braking units or faulty internal capacitors. S...

ovd Over-Voltage during Deceleration fault in delta drive troubleshooting Description The ovd fault is the classic "Regeneration" fault. It occurs when the DC bus voltage rises too high while the motor is slowing down. This is the most common over-voltage fault and is directly related to the physics of kinetic energy. Causes When an AC motor is mechanically driven faster than the synchronous frequency set by the VFD (which happens when you lower the frequency to stop), the motor acts as a generator. This "Regenerative Energy" flows back into the drive. The drive's rectifiers block it from going back to the grid, so it accumulates in the DC bus capacitors, raising the voltage until it trips. 1. Decel Time too Short: Trying to stop a heavy flywheel or high-inertia load too fast. 2. No Braking Resistor: The energy has nowhere to go. ...

ovn Over-Voltage during Constant Speed fault in delta drive troubleshooting Description ovn indicates the DC bus voltage is too high while the motor is running at a set speed. Since there is no deceleration occurring, regeneration shouldn't technically happen, making this fault indicative of input power or specific load types. Causes 1. Input Voltage High: The facility's transformer tap might be set too high, or there is unstable grid power. 2. Overhauling Load: If the load pushes the motor (e.g., a downhill conveyor belt or an elevator going down with a heavy load), the motor runs faster than the drive command, generating energy continuously. 3. Capacitor Issues: The drive's internal DC bus capacitors may be degrading, causing voltage ripple that is interpreted as peak over-voltage. Solution Focus on th...

Lv / LvA / Lvd Low Voltage fault in delta drive troubleshooting Description The Lv (Low Voltage) fault triggers when the DC bus voltage drops below a minimum threshold (e.g., < 190VDC for a 220V class drive). This ensures the IGBTs have enough voltage to gate properly and prevents the control electronics from shutting down unexpectedly. Causes 1. Input Phase Loss: One of the three input phases (R, S, T) is missing or a fuse has blown. The drive might run on single phase under light load but will trip Lv under load. 2. Low Mains Voltage: Brownouts or voltage sags in the facility. 3. Contactor Failure: The internal "Charge Relay" or contactor that bypasses the soft-charge resistor may have failed. If this doesn't close, the voltage drops immediately when the motor starts. 4. Sudden Load: A massive starting current draw on ...

oH1 Overheat (Heatsink) fault in delta drive troubleshooting Description oH1 indicates that the heat sink temperature sensor has detected a temperature exceeding the safe operating limit (usually 85°C to 90°C). This is a thermal protection mechanism to prevent the IGBT power modules from melting or exploding. Causes 1. Fan Failure: The cooling fans on the bottom or top of the drive are broken, jammed with dust, or running slowly. 2. Clogged Vents: The heat sink fins are clogged with cotton, dust, oil, or debris, preventing airflow. 3. High Ambient Temperature: The electrical panel is too hot (summer heat, no panel AC) or the drive is installed in direct sunlight. 4. Improper Mounting: No clearance space left above/below the drive for air circulation. Solution Cooling system maintenance: ...

oL1 Overload (Motor) fault in delta drive troubleshooting Description oL1 is the "Electronic Thermal Relay" protection for the motor. The drive calculates the motor's heat accumulation based on the current output and time (I²t). If the motor runs above its rated current for a prolonged period, oL1 trips to save the motor insulation. Causes 1. Heavy Load: The motor is undersized for the application, or the load has increased (worn bearings, dry gearbox). 2. Wrong Settings: The "Motor Rated Current" parameter (usually Pr.05-01) is set incorrectly (lower than the actual nameplate). 3. Low Speed Operation: Running a standard AC motor at low speeds (e.g., 10Hz) reduces its self-cooling fan efficiency, causing it to overheat even at rated amps. The drive calculates this derating. Solution Match th...

oL2 Overload (Drive) fault in delta drive troubleshooting Description oL2 protects the VFD itself. It indicates the drive is outputting more current than its internal components are rated for (e.g., 150% for 60 seconds). Unlike oL1 (which protects the motor), oL2 implies the drive is undersized for the task. Causes 1. Undersized Drive: The motor is larger than the drive, or the load requires torque that exceeds the drive's peak capacity. 2. High Friction: A mechanical bind is causing high current that doesn't quite trip instantaneous OC, but sustains high enough to heat up the drive logic. 3. V/F Mismatch: Excessive Torque Boost settings can cause high current saturation at low speeds. Solution Upgrade or adjust: 1. Upsize Drive: If the current draw is consistently near the drive’s max...

GFF Ground Fault fault in delta drive troubleshooting Description The GFF fault indicates the drive has detected a current leakage to ground (Earth) from the output terminals. The drive measures the sum of currents (U+V+W); if the sum is not zero, current is leaking elsewhere. Causes 1. Motor Insulation Failure: The motor winding insulation has degraded, shorting a phase to the motor housing. 2. Cable Damage: The output cable insulation is cut or chafed, touching the conduit or cable tray. 3. Moisture: Water has entered the motor terminal box or the conduit. 4. Long Cables: Extremely long motor cables can have high parasitic capacitance to ground, which the drive sees as leakage. Solution Critical safety check required: 1. Megger Test: Disconnect the motor cables from the dr...

PHL Phase Loss (Input) fault in delta drive troubleshooting Description PHL indicates that the drive has detected an imbalance or total loss of one of the incoming power phases (R, S, or T). Running on fewer phases stresses the DC bus capacitors and input rectifiers. Causes 1. Blown Fuse: One of the input fuses on the distribution panel has blown. 2. Loose Wire: A terminal screw on the input breaker or drive input is loose. 3. Grid Issue: The utility supply has dropped a phase. 4. Screw Terminal Corrosion: High resistance on one leg causing voltage drop. Solution Verify supply: 1. Measure Voltage: With the drive powered, carefully measure AC voltage between R-S, S-T, and T-R. They should be equal. 2. Check Fuses: Test continuity on all input fuses. ...

OPL Output Phase Loss fault in delta drive troubleshooting Description OPL signifies the drive is not detecting current on one of the output phases (U, V, W). This usually happens when the circuit to the motor is open. Causes 1. Disconnected Wire: A cable has come loose at the motor or drive end. 2. Motor Winding Open: The internal winding of the motor has burnt open. 3. Output Contactor: If there is a contactor or switch between the drive and motor, it might be open or have burnt contacts. 4. Drive Failure: One of the drive's output IGBTs is not firing. Solution Check the path to the motor: 1. Resistance Check: With power off, measure resistance between U-V, V-W, and W-U. All should be low and balanced. An infinite reading (OL) means a broken wire or winding. ...

EF / EF1 External Fault fault in delta drive troubleshooting Description The EF fault is not an internal drive problem. It is triggered by an external input signal wired to the drive's multi-function input terminals (MI1, MI2, etc.). The drive has been programmed to stop when this specific circuit opens or closes. Causes 1. Emergency Stop Pressed: An E-Stop button wired to the drive has been pushed. 2. Sensor Trip: An external sensor (vibration, pressure, auxiliary contact of a breaker) wired to a digital input has triggered. 3. Broken Wire: The control wire connected to the "External Fault" terminal is broken or loose. Solution Investigate external controls: 1. Check Inputs: Look at the drive display or LEDs to see which input (MI1, MI2, etc.) is active. Consult the wiring diagram...

cF1 Internal EEPROM Error fault in delta drive troubleshooting Description cF1 indicates a corruption in the internal memory (EEPROM) where parameters are stored. The drive cannot reliably read the saved settings. Causes 1. Power Failure during Write: Power was cut exactly while the user was saving a parameter or while the drive was performing a reset. 2. Electrical Noise: Severe electromagnetic interference corrupted the data transfer. 3. Hardware Failure: The memory chip on the control board has physically failed. Solution Attempt a reset: 1. Factory Reset: Perform a parameter reset to factory defaults (usually Parameter 00-02 set to 9 or 10). This clears the corrupted memory and rewrites default values. 2. Reprogram: Re-enter the necessary motor and application parameters...

cF2 Read/Write Error fault in delta drive troubleshooting Description Similar to cF1, cF2 indicates a failure to write data to the internal memory. This often happens during startup checks. Causes 1. Control Board Aging: Component degradation over time. 2. Loose Keypad: On some models, poor connection between the keypad and the drive can cause communication data errors mistaken for memory errors. 3. Power Instability: Unstable control voltage (low 24V or 5V rail). Solution Hardware check: 1. Power Cycle: Turn off the drive completely, wait for the display to go dark, and power on again. 2. Check Connections: Reseat the keypad and any ribbon cables connecting the control board to the power board. 3. Repair: If persistent, this requires professional board-...

HPF Hardware Protection Fault fault in delta drive troubleshooting Description HPF is a critical hardware failure message. It usually refers to the control circuit detecting a severe anomaly in the power section or current sensor feedback loop that is impossible to correct via software. Causes 1. Current Sensor Failure: The Hall Effect sensors measuring output current are giving impossible readings (e.g., current when stopped). 2. Thermistor Failure: The internal temperature sensor circuit is open or shorted. 3. Auxiliary Power Fault: The internal power supply generating +/- 15V for the gate drivers is failing. Solution This is rarely user-serviceable: 1. Reset and Retry: Power cycle the drive. 2. Service: If the fault appears immediately upon power-up (before running), the ...

PGF / PGF1 PG (Encoder) Feedback Error fault in delta drive troubleshooting Description For drives using closed-loop vector control with an encoder (PG card), PGF indicates a loss of feedback signal. The drive commands the motor to move but receives no pulse signal indicating movement, or the direction is reversed. Causes 1. Disconnected Encoder: Loose wiring between the encoder and the PG option card. 2. Incorrect Phasing: The A and B channels are swapped, making the drive think the motor is spinning backward. 3. Broken Coupling: The encoder shaft coupling is broken; the motor spins, but the encoder does not. 4. PG Card Failure: The option card mounted on the drive is faulty. Solution Check the feedback loop: 1. Wiring Check: Verify A, B, Z, Power, and Ground connections. S...

CE / CE10 Communication Error fault in delta drive troubleshooting Description CE faults relate to Modbus RS-485 or fieldbus communications. The drive has stopped receiving data packets from the PLC or controller for a time exceeding the timeout setting. Causes 1. Disconnected Cable: The RS-485 + or - wires are broken or loose. 2. Interference: Electrical noise from power cables is corrupting the communication signal (EMI). 3. Master Stopped: The PLC or controller has stopped polling the drive. 4. Wrong Settings: Baud rate, parity, or station address mismatch. Solution Restore communications: 1. Check Wiring: Ensure daisy-chain wiring is secure. Use shielded twisted-pair cable for RS-485. 2. Termination Resistor: Ensure a 120-ohm resistor is installed at...

bb Base Block (Status) fault in delta drive troubleshooting Description bb is technically a status, not a hard fault, but it often confuses operators. It stands for "Base Block," meaning the drive output is electronically blocked (IGBTs are off) and the motor is coasting. It appears when an external signal forces the drive to stop output immediately. Causes 1. External Signal: An input terminal programmed for "External Base Block" (N.O. or N.C.) has been activated. 2. Speed Search: During "Catch on Fly," the drive displays bb while sensing motor speed. 3. Interlock: Used often in elevator or crane applications to ensure the mechanical brake is engaged before the drive releases torque. Solution If bb is unexpected: 1. Check Digital Inputs: Identify which terminal is ...