Allen-Bradley 1336-SN-SP10A inverter snubber faults are commonly associated with excessive switching stress, inverter power component problems, loose electrical connections, or abnormal motor-side conditions rather than the snubber component alone. Effective troubleshooting requires analyzing the complete inverter protection system.

This article describes a field case where an Allen-Bradley 1336 drive experienced repeated overvoltage faults after replacing a snubber component.

Allen-Bradley 1336-SN-SP10A Inverter Snubber Fault Symptoms

Typical symptoms include:

• DC bus overvoltage alarms
• Drive trips during deceleration
• Motor stops unexpectedly
• Power module temperature increases
• Repeated component failure

Field case:

A production machine using an Allen-Bradley 1336 drive experienced frequent overvoltage trips during stopping.

Initial observations:

• Control functions operated normally
• Drive parameters were unchanged
• Fault occurred mainly during deceleration

The maintenance team suspected:

• Snubber failure
• DC bus capacitor problem
• Braking circuit issue

Engineers began troubleshooting from the inverter energy path.

Allen-Bradley 1336-SN-SP10A Fault Diagnosis Process and Voltage Analysis

Troubleshooting path:

Motor Energy Return
        |
        |
Inverter Power Section
        |
        |
Snubber Protection Circuit
        |
        |
DC Bus System

Engineers checked:

• Fault timing
• DC bus voltage
• Motor load condition
• Snubber connection

Diagnostic results:

• Control system: Normal
• Input power: Normal
• Fault occurred during energy regeneration

The problem was related to transient voltage management.

Allen-Bradley 1336-SN-SP10A Overvoltage Fault Investigation

Field measurements:

Before repair:

• DC bus voltage: Increased rapidly during stop command
• Fault timing: Deceleration stage
• Motor load: High inertia

Engineers analyzed:

• Deceleration settings
• Motor load characteristics
• Power protection components

The investigation found:

• Deceleration time was too short for the mechanical load

The inverter generated excessive regenerative energy, increasing stress on the DC bus and snubber circuit.

Allen-Bradley 1336-SN-SP10A Root Cause Analysis and Recovery

The final root cause was application-related regenerative stress.

Original condition:

• Normal load operation
• Stable braking performance

Changed condition:

• Increased machine inertia
• Faster stopping requirement

Failure pattern:

Normal condition:

• Controlled energy release

Fault condition:

• Excess regenerative energy
• DC bus voltage rise
• Protection activation

Engineering conclusion:

The snubber was operating as a protection device but the application conditions exceeded the original design parameters.

Allen-Bradley 1336-SN-SP10A Troubleshooting Repair and System Recovery

Corrective actions:

Drive Parameter Adjustment

Performed:

• Increased deceleration time
• Reviewed stopping profile
• Verified braking requirements

Power Section Inspection

Checked:

• Snubber condition
• DC bus components
• Power connections

Final results:

Before repair:

• Frequent drive trips
• Production interruptions

After repair:

• Stable stopping process
• Reduced electrical stress
• Reliable machine operation

Allen-Bradley 1336-SN-SP10A Common Fault Patterns and Diagnostic Methods

DC Bus Overvoltage Fault

Symptoms:

• Trip during deceleration

Diagnosis:

• Check braking conditions
• Review deceleration parameters
• Inspect snubber circuit

Repeated Snubber Damage

Symptoms:

• Protection component fails repeatedly

Diagnosis:

• Check IGBT condition
• Inspect power connections
• Analyze switching stress

Intermittent Inverter Fault

Symptoms:

• Random drive shutdown

Diagnosis:

• Review fault history
• Check electrical connections
• Inspect motor-side conditions

Allen-Bradley 1336-SN-SP10A Long-Term Maintenance Strategy

For reliable inverter operation:

• Inspect power connections regularly
• Monitor DC bus behavior
• Review motor load changes
• Check braking conditions
• Record fault trends

A practical engineering rule:

“When troubleshooting an Allen-Bradley 1336-SN-SP10A inverter snubber problem, identify the electrical stress source before replacing the protection component.”

Recommended troubleshooting sequence:

Fault history review → DC bus measurement → Power circuit inspection → Motor load analysis → Snubber verification → Final drive operation test.