West Valley Milling
Correcting 240V to 220V Three‑Phase Power for a New CNC Machine

Industry: Manufacturing — CNC Machining

Location: California

Challenge: A new CNC machine required 220V three-phase power, but the facility’s available service was 240V three-phase.

Solution: A three-phase buck/boost transformer was supplied and configured to step 240V down to 220V at the point of use so the machine could be commissioned at its required voltage.

The Challenge: The Building Voltage Didn’t Match the Machine Voltage

West Valley Milling in Chatsworth, California added a new CNC machine tool to expand production capability and keep work moving through the shop. The facility already had a stable electrical service in place: 240V three-phase power, a common voltage in industrial buildings.

The problem was that the new CNC machine was built to run on 220V three-phase. That meant the machine’s required voltage did not match what the building provided.

In a CNC environment, voltage mismatch is more than a spec-sheet detail. CNC machines often combine motors, drives, and control electronics that expect specific electrical conditions. If the machine is not operated at the voltage it was designed for, commissioning can become unreliable and long-term performance can be put at risk.

West Valley Milling needed a practical way to deliver the machine’s required 220V three-phase power without turning a single equipment add into a facility-wide electrical project.

Why This Matters: CNC Equipment Is Less Forgiving Than Typical Loads

On paper, 240V and 220V can sound close enough to “try it.” In a machine-shop setting, that approach can create unnecessary risk.

• Increased commissioning risk Running outside the machine’s intended voltage can contribute to nuisance faults, alarms, or unstable operation during startup.

• Higher stress on electrical components Overvoltage can increase stress on controls, drives, and power supplies designed around a specific input.

• Unpredictable performance under load CNC systems rely on consistent electrical conditions for repeatable operation; voltage mismatch can show up as inconsistent behavior when the machine is working.

• Expensive downtime When a production machine is down, the cost is not just the repair; it is the schedule disruption and lost output.

Because the CNC machine was a production-critical asset, West Valley Milling needed a correction approach that removed the mismatch rather than hoping the mismatch would be tolerated.

Why Changing the Facility Electrical Service Wasn’t the Answer

When a machine arrives with a different voltage requirement, the theoretical solution is to change the facility power to match.

In reality, changing service voltage can mean:

• additional cost and downtime

• delays while waiting on upstream electrical work

• impacts to other equipment already running in the facility
  

West Valley Milling needed a faster, permanent solution that corrected voltage for the CNC machine without reworking the entire building.

The Solution: A Three‑Phase Buck/Boost Transformer Configured for 240V → 220V

Sanzo Sales supplied a 50A three-phase buck/boost transformer configured to buck (step down) the facility’s 240V three-phase supply to the 220V three-phase level the CNC machine required.

A buck/boost transformer is designed for small, targeted voltage correction. Instead of changing the entire building service, it corrects the voltage difference at the point where the equipment needs it.

In this case, the solution allowed West Valley Milling to commission the CNC machine at its required operating voltage while keeping the facility’s existing 240V three-phase service intact.

Why This Was the Right Approach

• Correct voltage at the point of use The CNC machine receives the voltage it was built to run on, which supports reliable commissioning and ongoing operation.

• Avoids facility service changes Changing building service voltage or reworking distribution can be slow, expensive, and disruptive to other equipment already in use.

• A proven approach for small mismatches Buck/boost transformers are commonly used when the voltage difference is close enough to correct without an isolation transformer or service upgrade.

• Scales to real-world equipment adds When a facility adds equipment that does not match the existing service, buck/boost correction provides a repeatable way to integrate the right machine without redesigning the entire electrical system.
  

The Results

With the voltage correction in place, West Valley Milling was able to bring the CNC machine online at the correct operating voltage without changing the facility’s incoming service.

• CNC machine commissioned at required voltage The machine could be operated on 220V three-phase as specified.

• Reduced risk of voltage-related faults Correcting the mismatch reduced the likelihood of nuisance issues tied to operating at the wrong voltage.

• Avoided facility-wide electrical changes The building’s 240V three-phase service remained unchanged.

• Faster path to production Voltage correction was implemented as part of the machine installation process instead of delaying commissioning for service changes.
  

The end result was a clean, permanent correction that protected a major equipment investment and supported the shop’s production timeline.

Why Voltage Mismatches Happen When Adding CNC Equipment

Voltage mismatches are common in manufacturing and machine shops because facility power and equipment requirements do not always align.

1. Standard building voltages are limited. Most facilities are built around a small set of common service voltages, and those voltages often remain in place for decades.

2. Equipment is built to multiple voltage standards. CNC machines and specialized industrial equipment may be designed around 220V, 230V, 240V, or other standards depending on the manufacturer and market.

3. Production needs drive purchasing decisions. Shops buy the equipment that fits capacity, lead time, and performance requirements, even when the voltage does not perfectly match the building.

4. The mismatch is usually discovered at commissioning. The voltage issue becomes urgent when the machine is on the floor and needs to run, which is why a fast, permanent correction method matters.
   

When the voltage difference is within a practical correction range, buck/boost transformers are a standard method for closing the gap without a service upgrade.

Frequently Asked Questions

What is a buck/boost transformer?

A buck/boost transformer is a compact transformer used to raise (boost) or lower (buck) voltage by a small amount so the supply matches equipment requirements.

Does a buck/boost transformer change phase?

No. Buck/boost transformers correct voltage but do not convert single-phase to three-phase or vice versa.

Is a buck/boost transformer the same as an isolation transformer?

No. Buck/boost transformers are commonly used for voltage correction and are often applied as autotransformers. If isolation is required for a specific application, that is a different selection.

What information is needed to quote a three-phase buck/boost transformer for a CNC machine?

Typically: the machine’s required voltage and phase, the facility’s available voltage and phase, the machine load (amps/FLA or kVA), duty cycle, and installation environment.

Can a facility use one buck/boost transformer for multiple machines?

Sometimes, but it depends on whether the machines share the same correction requirement and whether the combined load is within the transformer’s rating. This should be evaluated by a qualified electrician as part of the electrical design.

Key Takeaways

• Correct voltage matters for CNC machines Voltage mismatch can increase commissioning risk and long-term reliability issues.

• Small voltage differences are common Facilities often have standard service voltages while machines may require a different standard.

• Buck/boost is a targeted solution It corrects the voltage difference at the point of use without changing facility service.

• Three-phase correction requires the right approach Voltage and phase must match equipment requirements for reliable operation.

• A repeatable method supports growth Voltage correction helps shops add the best equipment available without redesigning building power.

Have printing or production equipment that needs a different voltage than your facility provides? Buck/boost transformers are the industry-standard solution. To learn more about solving voltage mismatch challenges, contact Sanzo Sales.