Yaskawa F7 Drive Programming

A BUS fault indicates an issue with the communication option board installed in the drive. This occurs when there's a problem with the drive's ability to communicate over its industrial network (e.g., Modbus, Ethernet/IP, Profibus). This can be caused by wiring errors, incorrect communication settings, or a hardware failure of the option board itself. Loss of communication means the drive cannot receive commands or send status updates via the network, potentially stopping operations.

This fault indicates a loss of serial communication (e.g., Modbus) between the drive and its control system for more than 2 seconds, affecting parameters like H5-04 and H5-05. The drive will execute a programmed stopping method, becoming unresponsive to external commands. Prolonged communication loss can lead to process interruption and potential safety hazards if the drive is not properly controlled.

A CPF5 fault indicates a critical internal issue with the drive's CPU Analog-to-Digital (A/D) converter. This is a hardware malfunction within the drive's control board, meaning the drive cannot accurately measure and process internal signals. If this fault occurs, the drive is unable to function correctly and requires internal repair or replacement.

A Speed Deviation (DEV) fault is triggered when the difference between the actual motor speed and the frequency reference command exceeds the configured deviation level (F1-10) for a time longer than F1-11. This signifies a discrepancy between the commanded speed and the actual motor speed, often due to mechanical load issues, encoder problems, or improper tuning of the speed control loop. Prolonged deviation can lead to process quality issues, mechanical stress on components, or inefficient operation.

An EF0 fault is triggered by an external fault signal received from a communication option board. This mechanism allows an external system or safety device to signal a fault condition to the drive, causing it to stop according to the stopping method defined by parameter F6-03. This is typically used for integrating safety interlocks, external protection devices, or higher-level system faults into the drive's fault logic.

A GF fault occurs when the current to ground on the output side of the drive exceeds 50% of the drive’s rated output current. This is determined by comparing the measured current on each of the output phases, indicating a leakage path from the motor or its associated output cabling to ground. This is a serious fault that poses a significant safety hazard and can lead to severe damage to the drive, motor, or other connected equipment if not immediately addressed.

An LF fault signifies that one or more of the output phases to the motor has been lost. The drive monitors the RMS current value for each phase and triggers the fault if the current decreases to or below an internal detection level for 10 seconds. This can be caused by a broken motor lead, a loose connection at the motor or drive, or an internal motor winding failure. Operating with an output phase loss can lead to motor overheating, damage to the motor and drive, or severe process disruptions.

An OH pre-alarm is issued when the heatsink temperature exceeds the L8-02 level, acting as an early warning before an OH2 fault trip. Depending on L8-03, the drive may continue running or continue running at a reduced speed. This signals that the heatsink is approaching its overtemperature limit and corrective action may be needed to prevent a full fault trip and subsequent shutdown.

An OH2 fault occurs when any of the heatsink thermistors measure a temperature exceeding the level set in L8-02. This indicates that the drive's heatsink is overheating, typically due to insufficient cooling, excessive ambient temperature, or prolonged overload on the drive. Sustained high temperatures can severely degrade the lifespan of the drive's power components and lead to premature failure.

This alarm signals that the motor's temperature has reached an elevated state, specifically when the motor temperature analog input (H3-09=E) exceeds the 1.17V threshold (OH3 level). It serves as an early warning for potential overheating, but does not stop the drive unless configured to do so. Ignoring this alarm could lead to a more severe OH4 fault or motor damage if temperatures continue to rise.

The OH4 fault indicates a critical over-temperature condition in the motor, detected when the motor temperature analog input (H3-09=E) surpasses the 2.34V fault level. Upon activation, the drive will immediately stop the motor using a configured method to prevent damage. Operating a motor under this severe overheat condition risks immediate insulation breakdown, permanent motor failure, and safety issues.

The OL1 fault is triggered when the motor connected to the drive experiences prolonged overcurrent, causing it to exceed its thermal capacity. This protection is configured by parameters like L1-01 (protection selection) and L1-02 (overload time constant). Continuing to operate a motor in an OL1 condition severely risks damage to motor windings and insulation, leading to premature motor failure and costly downtime.

An OL3 condition indicates an overtorque situation where the motor's output torque exceeds the configured L6-02 level for the duration set in L6-03. This can be set as either an alarm or a fault and can be detected continuously or only when at speed agreement. It typically signifies a jam, excessive mechanical load, or an obstruction in the driven equipment. Unresolved overtorque can lead to motor overheating, mechanical damage, or drive trip.

This fault indicates that the motor load has exceeded the configured Overtorque 2 detection level (L6-05) for the set duration (L6-06). Similar to OL3 but using a secondary profile, it triggers based on L6-04 settings, causing the drive to shut down. This points to a mechanical obstruction, jamming, or excessive resistance in the driven equipment. If persistent, this can lead to motor and drive damage or mechanical failure of the connected machinery.

An Overspeed (OS) fault occurs when the motor speed feedback, typically from the PG, exceeds the configured overspeed detection level (F1-08) for a duration longer than the delay time (F1-09). This indicates the motor is running faster than its allowed maximum, potentially due to incorrect control parameters, regenerative load conditions, or an encoder issue. Unresolved overspeed can lead to mechanical damage to the motor or driven equipment, and create safety hazards.

A PF fault indicates that one or more of the input AC phases to the drive has been lost. The drive's detection circuit monitors DC bus current ripple and activates if the difference (ΔV) between maximum and minimum DC bus voltage values reaches or exceeds an internal detection level for 0.5 seconds. This can lead to imbalanced current draw, potential damage to the drive's input rectifier, and motor instability.

This fault occurs when an open circuit condition is detected in the Pulse Generator (PG) feedback. This means the drive is not receiving proper speed or position feedback from the motor's encoder. This can lead to uncontrolled motor speed, position errors, or loss of precise control if left unaddressed.

A UL3 condition signifies an undertorque situation where the motor's output torque drops below the configured L6-02 level for the duration set in L6-03. This can be set as either an alarm or a fault and detected continuously or only when at speed agreement. It often indicates a broken belt, loss of load (e.g., a pump running dry or a disconnected shaft), or a mechanical failure that reduces the required torque. Unresolved undertorque can lead to inefficient operation or potential damage to equipment (e.g., pump cavitation).

This fault occurs when the motor's torque output drops below the Undertorque 2 detection level (L6-05) for the set duration (L6-06). This secondary undertorque profile triggers based on L6-04 settings, causing the drive to shut down. It typically signifies a loss of mechanical load, such as a broken belt, coupling failure, or material feed issue. Unresolved undertorque can lead to runaway motor conditions, process material loss, or damage from unsupported operation.

An Undervoltage (UV) alarm is displayed on the digital operator during a momentary power loss event, specifically after power loss but before a fault trip occurs. This indicates that the drive is actively attempting to ride through the power loss, maintaining operation as long as control power is sustained. It's a warning, not a fault that stops the drive immediately.

The UV1 fault occurs when the drive detects a loss of AC input power or when the DC bus voltage drops below the set undervoltage trip level, defined by parameter L2-05. This typically affects the power supply circuit within the drive. If not addressed, the drive cannot operate reliably and will shut down, potentially disrupting the entire controlled process.