Okay, this is a common issue with VFDs and GFCI protection, especially in wet environments like breweries. Here's a breakdown of the problem and potential solutions

The Problem:
VFD Leakage Current

VFDs inherently have some leakage current to ground. This is due to the internal components (capacitors, filters, etc.) and how they switch power to the motor.

Low GFCI Trip Threshold

Standard 6mA GFCI breakers are designed to protect personnel from even small electrical shocks. They are very sensitive, and the inherent leakage from the VFD exceeds this threshold, causing nuisance tripping.

Wet Environment

The wet location exacerbates the problem. Moisture can increase the leakage current paths, making it even more likely to trip the GFCI.

Safety Concerns

You can't just ignore the need for GFCI protection in a wet environment. It's crucial for safety.

The potential solutions


Do Not Disable GFCI protection

Disabling GFCI protection is not an option. The purpose of the GFCI protection is to save lives. In a commercial environment, it is especially important.2.

GFCI Breakers with Higher Trip Thresholds



Search for 30mA GFCI Breakers

The manufacturer's recommendation of a 20mA GFCI is ideal, but finding one rated at 30mA would be acceptable if a 20mA cannot be located.

Look for Industrial-Grade GFCI Breakers

Some manufacturers offer GFCI breakers specifically designed for industrial applications. These might have higher trip thresholds (around 30mA) and better filtering to reduce nuisance tripping while still providing adequate protection.3.

Isolation Transformer



Install an Isolation Transformer

Place an isolation transformer upstream of the VFD. This creates a separately derived system. The neutral of this new system is bonded to ground at the transformer. This isolates the VFD's leakage current from the main electrical system, hopefully preventing the GFCI from tripping.

Sizing

Ensure the transformer is properly sized for the VFD's input requirements (voltage, current, kVA). Add some headroom for future expansion (e.g., 20-25%).

GFCI Placement

Place the GFCI breaker on the secondary side of the isolation transformer. This protects personnel from faults within the newly isolated system.

Benefits

Provides a cleaner ground reference and helps prevent leakage currents from the VFD from affecting the main electrical system.4.

Line Reactor



Install a Line Reactor Install a line reactor on the input side of the VFD. This will help smooth the AC voltage and reduce the current harmonics generated by the VFD. The reduced harmonics will reduce the leakage current.5. Careful Grounding and Bonding



Proper Grounding

Ensure the VFD is properly grounded according to the manufacturer's instructions and local electrical codes. A solid, low-impedance ground path is essential.

Bonding

Bond all metal enclosures (VFD cabinet, motor frame, conduit) together to create an equipotential plane. This minimizes voltage differences and reduces the risk of shock.

Dedicated Ground Wire

Use a dedicated equipment grounding conductor (EGC) from the panel to the VFD and then to the motor. Don't rely solely on conduit as the ground path.6.

Filter Installation



Install a filter on the output

If you are using a shielded cable between the VFD and the motor, install a filter on the output terminals of the VFD to ground. These filters are designed to reduce ground currents.

Important Considerations and Recommendations



Consult with a Qualified Electrician

This is not a DIY project. A licensed and experienced electrician familiar with VFDs and industrial electrical systems must be involved. They can properly assess the situation, choose the right solution, and ensure the installation meets all applicable codes and safety standards.

Manufacturer Support

Continue working with the VFD manufacturer's technical support. They may have specific recommendations or solutions tailored to their product and your application.

Documentation

Document all changes made to the electrical system, including the installation of any new components (isolation transformer, filters, etc.). Keep this documentation readily available for future reference and maintenance.

Regular Testing

After installation, periodically test the GFCI breaker to ensure it is functioning correctly.

In Summary:

Your primary focus should be to find a GFCI solution that offers adequate safety without* causing nuisance tripping. Start by exploring the higher trip threshold options (20mA or 30mA industrial GFCIs). If that doesn't work, consider an isolation transformer combined with proper grounding and bonding practices. The wet environment adds complexity, so professional electrical expertise is essential. Flag for review