Table of Contents

• Installation Overview of 1321-M048 Common Mode Choke
• Role in VFD EMI Suppression System
• Pre-Installation Electrical & Mechanical Checks
• Mechanical Mounting & Thermal Layout
• Power Wiring & Phase Routing Rules
• Grounding & Shielding Requirements
• Commissioning & Drive Performance Verification
• FAQs on 1321-M048 Installation
• Engineering Summary & Field Practices

Installation Overview of 1321-M048 Common Mode Choke

The Allen-Bradley 1321-M048 common mode choke is designed to reduce electromagnetic interference (EMI) generated by variable frequency drives (VFDs). Proper installation directly affects motor performance, drive stability, and compliance with industrial EMC standards.

Role in VFD EMI Suppression System

The 1321-M048 reduces high-frequency common mode currents between VFD output and motor windings. It helps minimize ground leakage current, motor bearing stress, and electromagnetic noise affecting nearby PLC and sensor systems.

Pre-Installation Electrical & Mechanical Checks

• Verify VFD output current rating matches choke specification
• Check motor cable insulation and shielding condition
• Ensure installation environment allows adequate airflow
• Confirm no damage or cracks in choke core or terminals
• Review cable length requirements between VFD and motor

Mechanical Mounting & Thermal Layout

1. Mount choke close to VFD output terminals
2. Maintain vertical orientation for optimal cooling
3. Ensure clearance from heat sources and power resistors
4. Avoid mounting near high-vibration equipment

Field experience shows that poor airflow around the choke can increase operating temperature by more than 15°C under continuous load.

Power Wiring & Phase Routing Rules

• Route all three phases (U/V/W) through the choke simultaneously
• Do not bypass any phase or create partial routing
• Maintain tight cable loops to reduce EMI radiation
• Use correctly rated VFD output cables only

WIRING_CHECK /MODEL=1321-M048 /PHASE_VERIFY /OUTPUT_ROUTING /EMI_COMPLIANCE

Grounding & Shielding Requirements

• Connect motor cable shield to ground at VFD side only
• Ensure low impedance grounding between VFD and cabinet frame
• Avoid multiple grounding points on output side

In one commissioning case, improper dual grounding caused circulating currents and unexpected VFD fault trips until corrected.

Commissioning & Drive Performance Verification

• Start VFD at low frequency and monitor output waveform
• Check motor noise and vibration levels under load
• Measure leakage current before and after choke installation
• Monitor VFD fault log during acceleration cycles
• Verify EMI reduction in nearby control circuits

FAQs on 1321-M048 Installation

Where should the choke be installed in relation to the VFD?

It should be installed as close as possible to the VFD output terminals to minimize cable-induced EMI.

Can one phase be routed separately?

No. All three phases must pass through the choke equally to ensure proper magnetic balance.

Does the choke affect motor torque?

Under correct installation, torque impact is negligible; improper wiring may cause performance degradation.

Engineering Summary & Field Practices

The Allen-Bradley 1321-M048 common mode choke is a critical component for VFD EMI suppression. Correct installation requires strict adherence to phase routing, grounding discipline, and physical placement rules. Field experience confirms that most performance issues are installation-related rather than product defects, and proper engineering practice ensures stable motor operation and reduced electromagnetic interference.