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Yaskawa A.720 Overload Alarm: Causes, Troubleshooting & Repair Guide
Error Overview
- Alarm Code: A.720
- Type: Overload Alarm
- Category: Servo / Motion Load
- Severity: High (can stop robot during operation)
- Related System: Servo motor, gearbox, mechanical transmission
Field insight:
In real-world applications, A.720 is almost never a random electrical fault.
It usually means the motor is being pushed beyond its continuous torque limit due to load, friction, or system mismatch.
What Does Yaskawa A.720 Alarm Mean?
The A.720 alarm is triggered when the servo motor operates under excessive load for a sustained period, not just a momentary spike.
In simple terms:
The motor is working harder than it was designed to — and the system shuts it down to prevent overheating or damage.
This is what makes A.720 different from:
- A.710 (overcurrent → electrical spike)
- A.720 (overload → continuous stress)
Quick Fix (5-Minute Check First)
Before deep troubleshooting, try th is:
- Reduce payload or external load
- Check for collision or mechanical obstruction
- Restart after motor cools down
- Run the axis at lower speed
If the alarm disappears under lighter load → it's almost certainly a mechanical overload issue.
Common Symptoms
- Robot stops during acceleration or heavy motion
- Alarm appears only under load
- axis movement becomes slow or unstable
- Alarm resets but returns during operation
- Motor temperature rises abnormally
Main Causes of A.720 Alarm
1. Mechanical Overload (Most Common)
- Payload exceeds rated capacity
- Tooling weight distribution is poor
- External forces or process resistance
This is the #1 root cause in most cases.
2. Mechanical Resistance / Binding
- Worn bearings
- Gearbox wear or internal friction
- axis misalignment
- Foreign objects blocking movement
Key sign: axis feels stiff even when servo is OFF.
3. Incorrect Motion Parameters
- Acceleration too aggressive
- Speed set too high
- Poor motion path planning
Often occurs after:
- System reconfiguration
- Parameter modification
4. Servo Motor Degradation (Less Common)
- Internal friction increases
- Efficiency drops over time
- Higher current required for same load
How to Troubleshoot Yaskawa A.720 Overload Alarm
A.720 troubleshooting should always begin from the mechanical side before touching drive parameters, because most cases are physically induced.
Step 1 – Identify When the Alarm Appears
- Startup → possible mechanical jam or incorrect configuration
- During motion → load or friction-related issue
- After long operation → thermal accumulation or degradation
Step 2 – Check Mechanical Resistance First
Manually or safely test whether the system moves freely.
Ask:
- Does the axis rotate smoothly without power?
- Is there any stiffness, grinding, or resistance?
Mechanical resistance is the most frequent root cause of A.720.
Step 3 – 5-Minute Load Isolation Test
Disconnect the motor from the mechanical load and run it under no-load conditions.
- If A.720 disappears → mechanical overload confirmed
- If A.720 remains → motor or drive-side issue
This is the fastest way to separate mechanical vs electrical origin.
Step 4 – Verify Load vs Motor Capacity
Check whether:
- Actual torque demand exceeds motor rated torque
- Application was modified after commissioning
- Load inertia increased over time
Step 5 – Evaluate Motor Condition
Inspect:
- Temperature rise under normal operation
- Abnormal vibration or noise
- Current draw trend compared to baseline
Step 6 – Review Parameters
Check:
- Acceleration / deceleration profiles
- Torque limits
- Servo tuning after system changes
Key Diagnostic Signs of Yaskawa A.720 Overload Fault
- Gradual overload development → mechanical wear or undersized motor
- Overload after parameter change → tuning/configuration issue
- Overload with high motor temperature → motor degradation likely
Recommended Parts for A.720 Repair
Once the root cause is confirmed, the issue is usually related to one of the following components:
-
Servo Motors
If the motor shows overheating, reduced efficiency, or insufficient torque output, replacement may be necessary—especially in aging systems. In these cases, selecting the right model from your existing Yaskawa servo motorsrange ensures stable long-term operation under load. -
Gearbox / Reducer
When internal wear or friction increases torque demand, the gearbox becomes a key factor. A worn reducer can continuously force the motor into overload, even if the motor itself is still functional. Restoring smooth mechanical transmission is critical to eliminate recurring A.720 alarms. -
Motor Cables (Secondary Check)
Although less common, damaged or degraded cables can lead to unstable feedback or power delivery. If you suspect signal issues, it’s worth checking your Yaskawa motor cablesfor wear, looseness, or insulation failure.
Yaskawa A.720 Alarm: Repair or Replace Decision Guide
Repair (Limited Cases)
- Parameter tuning
- Load adjustment
- Minor mechanical correction
⚠️ Risk: overload often returns if root cause is structural
Replace
- Motor operates near thermal limit
- Load permanently exceeds design capacity
- Mechanical system cannot be reduced
Replacement provides stable long-term operation under real production load.
Prevention Tips
- Keep payload within rated limits
- Avoid aggressive acceleration settings
- Perform regular mechanical inspection
- Maintain proper lubrication
- Monitor motor temperature trends
Related Yaskawa Alarm Codes
Understanding these Yaskawa Alarm Codes can help identify the true root cause.
FAQ
Can I ignore A.720 if it resets after restart?
No. It indicates ongoing overload and may cause long-term damage.
Is A.720 caused by the servo drive?
Rarely. Most cases are mechanical or load-related.
Do I need to replace the motor immediately?
Not always. Only if overheating or degradation is confirmed.
Can parameter tuning fix it?
Only if caused by configuration. Physical overload cannot be tuned away.
Explore the Full Guide: Industrial Robot Fault Codes Library → Yaskawa Alarm Codes
Explore the complete guide for troubleshooting, repair strategies, and component replacement across industrial robot systems.
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