You need to replace the 200 amp breaker with a properly sized breaker for the VFD. Keeping the 200 amp breaker is a serious safety hazard.

Here's why and how to determine the correct breaker size

Why you MUST change the breaker:
VFD Overload Protection

VFDs have built-in overload protection. The VFD will trip its internal protection if the motor draws excessive current. However, a 200 amp breaker will likely

not trip quickly enough to protect the VFD's sensitive components from damage if a fault occurs within the VFD or motor. The VFD overload protection is designed to protect the motor, not necessarily the VFD itself from a catastrophic fault. Selective Coordination

The purpose of a breaker is to protect the wire from overcurrent. A properly sized breaker protects the conductor and the load. A 200 amp breaker is protecting the wire but not the VFD.

Code Compliance

Electrical codes (like the NEC in the US) require overcurrent protection to be appropriately sized for the connected load. Using a grossly oversized breaker violates these codes.

Arc Flash Hazard

A larger breaker increases the potential arc flash hazard during a fault condition.

How to Determine the Correct Breaker Size


VFD Nameplate Data

The VFD nameplate will provide a maximum input current rating (sometimes called "Input Amps" or "Continuous Input Current"). This is a crucial starting point.2.

Motor Full-Load Amps (FLA)

Find the motor's FLA from its nameplate. You will likely need to derate it based on the motor's service factor (if greater than 1.0)3.

VFD Manufacturer Recommendations

The VFD's installation manual will have specific recommendations for input breaker size. This is the

most important source of information. The manufacturer has already taken into account the VFD's characteristics and provides the safest and most effective breaker size.4. NEC (National Electrical Code)

The NEC provides guidelines for overcurrent protection. You will need to consult the relevant sections (especially those pertaining to motors and VFDs) to ensure compliance.5.

Calculations (If Necessary)

If the VFD manual doesn't provide a specific breaker size, you may need to calculate it based on the VFD's input current rating and any applicable derating factors from the NEC. A common starting point is to size the breaker at 125% of the VFD's continuous input current rating.

Example

Let's say: The VFD nameplate says "Maximum Input Current: 45 Amps" The VFD manual recommends a 60 Amp breaker. NEC allows sizing the breaker at 125% of the continuous input current. 125% of 45A is 56.25AIn this case, you should use a

60 Amp breaker. The manufacturer is giving you the right size in the instruction manual.

Important Considerations



Service Factor

If the motor has a service factor greater than 1.0, you may need to adjust the FLA used in your calculations.

Ambient Temperature

High ambient temperatures can affect breaker ratings. Consult the breaker's manufacturer's data sheet.

Type of Breaker

The VFD manual may specify a particular type of breaker (e.g., inverse time, instantaneous trip).*

Wiring

Ensure the wire gauge is appropriate for the new breaker size. It must be sized to the overcurrent device.

Steps to Take


Consult the VFD Manual

This is your

primary source of information.2. Gather Data

Get the VFD and motor nameplate data.3.

Calculate (If Needed)

Perform the necessary calculations, using the VFD's input current rating.4.

Choose the Correct Breaker

Select a breaker that meets the VFD manual's recommendations and complies with the NEC.5.

Install the Breaker

Have a qualified electrician install the new breaker and ensure all wiring is correct.

Warning: Working with electricity can be dangerous. If you are not a qualified electrician, do not attempt this work yourself. Hire a licensed electrician to ensure the installation is safe and code-compliant.In summary, the 200 amp breaker is not suitable for the VFD and needs to be replaced with a properly sized breaker based on the VFD's input current requirements and the manufacturer's recommendations. Failure to do so is a significant safety hazard. Flag for review