Siemens SINAMICS G120 vs G220: How to Choose for Replacement, Retrofit, and New Projects

A failed SINAMICS G120, a planned panel upgrade, and a new machine design may all lead to the same question: should you continue with G120 or move to G220? The answer should not be based only on which platform is newer. A G220 should not be treated as an automatic drop-in replacement for every G120 configuration.

The practical decision is to choose among three paths: keep the existing G120 system, replace it with a verified G120 configuration, or engineer a migration to G220. This guide compares the two platforms through compatibility, commissioning, safety, bill of materials, downtime, and total installed cost.

Quick Verdict: Which Path Fits Your Project?

An urgent repair and a planned modernization should not follow the same decision process. If production must restart within hours, changing the drive platform may introduce cabinet work, PLC changes, parameter rebuilding, and new validation tasks. A planned project has more room to compare these costs against the benefits of G220.

For new machinery, there is no existing wiring or parameter set to preserve. The selection can start with the motor, duty cycle, machine safety concept, network standard, commissioning method, and spare parts policy.

Architecture: Why G120 and G220 Are Not Interchangeable by Default

How the G120 Modular System Works

SINAMICS G120 is a modular drive family. A typical configuration combines a Power Module, a Control Unit, and an optional operator panel. The Power Module handles the motor power stage, while the Control Unit determines many control, communication, I/O, and safety capabilities.

This means that "G120" alone is not a complete replacement specification. The PM, CU, panel, firmware, and accessories must be identified. Siemens describes this modular arrangement and provides different CU and PM combinations for different requirements.

For product-level sourcing, see our SINAMICS G120 frequency converter page. For a broader view of available families, visit the Siemens VFD category.

How G220 Changes the Configuration Approach

SINAMICS G220 is configured around a drive unit with communication modules, option modules, and commissioning tools selected for the application. Siemens documents an integrated web server, compatibility with Startdrive in TIA Portal, an optional Smart Adapter for wireless access, and plug-in communication options.

The exact hardware, protocol, safety functions, enclosure, and power-quality features still depend on the selected variant and options.

The architectural difference matters because a migration cannot be planned by matching only voltage and kilowatts. It may change mounting, terminals, PLC hardware configuration, parameter handling, service procedures, and the spare parts strategy.

G120 vs G220: Differences That Change the Engineering Decision

The table is a screening tool, not a substitute for the current manual and data sheet. G120 capabilities vary with the PM, CU, and firmware. G220 capabilities also vary by order number, communication module, software option, enclosure, and product variant.

Siemens lists the G220 Clean Power solution separately, so its harmonic performance should not be generalized to the entire G220 family.

Serviceability and Spare Parts

A plant standardized on G120 may already hold compatible Power Modules, Control Units, operator panels, parameter backups, and trained maintenance staff. That existing investment can make a verified G120 replacement the lower-risk choice even when another platform offers newer functions.

For G220, the service model should be assessed around the complete drive configuration. Determine which unit or module would be replaced after a fault, where the parameters are stored, which tools are needed, and what spares must be stocked.

Motor Control and Load Type

Do not select either drive from the application name alone. A pump, fan, conveyor, mixer, or centrifuge can have very different torque, overload, acceleration, braking, and speed-control requirements.

Collect the motor rated current, voltage, power, speed, efficiency class, motor type, feedback device, minimum operating speed, overload duration, and load inertia.

G220 documentation highlights high-performance motor control and support for high-efficiency motor concepts, but the final selection must still be verified for the exact motor and operating point.

PLC Communication and Commissioning

"Both drives support PROFINET" is not enough to confirm compatibility.

Check the communication hardware, telegram, GSD or GSDML file, device name, IP address, I/O mapping, diagnostics, and PLC hardware catalog entry. Also confirm the TIA Portal or Startdrive version and the firmware of the installed equipment.

A protocol match may still require PLC engineering and retesting. This is often one of the largest hidden tasks in a G120 to G220 migration.

Safety and Compliance

The presence of Safe Torque Off does not prove that two drive configurations are safety-equivalent. Confirm the required safety functions, input wiring, safety PLC logic, target PL or SIL, regional approvals, and machine acceptance procedure.

Siemens documents extensive Safety Integrated functions for G220, including STO as a standard function and higher safety ratings for applicable configurations. These product capabilities do not replace the machine risk assessment or the need to validate a modified safety system.

When Keeping or Replacing G120 Makes More Sense

Continuing with G120 can be the stronger decision in three common situations.

First, production downtime is tightly limited and the existing mechanical, electrical, PLC, and safety design is already validated. A verified replacement can reduce the number of changed variables.

Second, the plant has standardized its spares and maintenance procedures around G120. Existing PMs, CUs, panels, project files, and technician experience may have significant operational value.

Third, the application has no new motor, communication, safety, diagnostic, or power-quality requirement. A migration should solve a defined problem. "Newer" by itself is not a business case.

Pause a migration if the original parameters are not backed up, the PLC and safety scope is unknown, the cabinet has not been measured, accessory compatibility is unconfirmed, or no rollback plan exists.

For a broader explanation of keep, replace, and platform-conversion decisions, see our DC Drive Retrofit Guide. That guide covers the general retrofit method, while this article focuses specifically on G120 and G220.

When G220 Deserves Serious Evaluation

G220 becomes a stronger candidate when the project has a clear requirement that is not efficiently met by the current design.

For a new machine, the team can evaluate the platform without preserving existing terminals, dimensions, PLC objects, or spare parts. This is the right time to compare commissioning workflow, connectivity, motor strategy, safety concept, cybersecurity requirements, enclosure, and future service model.

For a planned modernization, G220 may deserve evaluation when the project introduces a new motor type, more demanding control, additional diagnostics, different communication, stronger security requirements, or a revised power-quality concept.

Siemens positions G220 around high-performance control, digital commissioning, Security Integrated, and configurable hardware and software options. The value of these functions should be tied to a specific machine or plant requirement.

A migration is most manageable when there is a defined engineering budget, a test environment, an approved shutdown window, FAT or SAT criteria, and a practical rollback plan.

Is G220 a Direct Replacement for G120?

Usually, it should be treated as an engineered migration until the exact configurations are proven otherwise.

A drop-in replacement needs little or no change to mounting, power wiring, control wiring, or software. A functional replacement performs the required job but needs adaptation. An engineered migration includes mechanical, electrical, software, safety, and validation work.

Use the following checklist before approving a G120 to G220 change:

Do not mark an accessory as reusable because the voltage appears similar or the connector fits. Check current rating, function, wiring, thermal conditions, approvals, and the exact drive documentation.

Build the Complete BOM and Compare Total Installed Cost

Before requesting a quotation, document the existing G120 configuration. Record the complete PM and CU order numbers, operator panel, memory card, communication interface, safety configuration, line and motor-side components, braking hardware, firmware, software version, and clear nameplate photos.

Then define the required G220 configuration from the application rather than selecting an isolated drive order number. Include voltage, rated current, duty class, motor type, communication, safety, enclosure, operator access, feedback, line-side components, motor-side components, and regional approvals.

Classify every item as:

• Confirmed reusable
• Not reusable
• Requires engineering or supplier verification
• Recommended for replacement

You can use our Siemens model library to begin identifying part numbers, but final compatibility must be checked against the current product documentation and the complete application.

Compare both alternatives with the same scope:

Total installed cost = drive and accessories + cabinet and wiring + engineering and validation + planned downtime + training and spares

The drive price alone can be misleading. A lower hardware price may still result in a higher project cost if it requires cabinet changes, PLC redevelopment, safety validation, longer commissioning, or new spare parts.

Likewise, a more expensive drive may be justified only when its functions create measurable operational value.

A Five-Step Selection Workflow

1. Collect the Existing System and Application Data

Gather the complete drive BOM, motor nameplate, load profile, PLC and network information, safety requirements, cabinet conditions, environment, shutdown limits, and commercial requirements.

2. Eliminate Incompatible Options

Reject any configuration that fails a mandatory electrical, motor, mechanical, thermal, safety, environmental, or approval requirement. Do this before comparing price.

3. Compare Keep, Replace, and Migrate

Evaluate all three paths with the same criteria: function, risk, downtime, hardware, engineering, validation, spares, and lifecycle support.

4. Validate Exact Order Numbers and Current Documents

Confirm the drive, modules, accessories, firmware, software, drawings, manuals, and regional approvals. Do not use a family-level blog as the final configuration record.

5. Approve the BOM, Test Plan, and Rollback Plan

Before purchase, assign responsibilities and approve the parameter backup, acceptance criteria, shutdown plan, test sequence, spare requirements, and rollback trigger.

What to Send SZCT Automation for an Accurate Review

SZCT Automation supplies industrial automation products and supports customers with product selection and application-oriented sourcing across PLC, VFD, HMI, and related categories. The company presents industry solutions for energy, manufacturing, water, transportation, food and beverage, and other automation applications.

For a G120 replacement or G220 migration review, send:

• Complete G120 PM and CU order numbers
• Photos of the drive, nameplates, terminals, and cabinet
• Motor nameplate and motor type
• Supply voltage and frequency
• Application and load description
• Speed range, overload, braking, and regeneration requirements
• PLC model, protocol, telegram, and software version
• Safety functions and required PL or SIL
• Reactors, filters, braking resistor, encoder, and other accessories
• Quantity, destination country, required date, and certification needs

Submit the information through our inquiry page. The site states that a sales representative will follow up after receiving an inquiry.

FAQ

 

 

Is SINAMICS G220 a Direct Replacement for G120?

Do not assume it is. A direct replacement requires verified mechanical fit, electrical ratings, terminal functions, PLC communication, safety behavior, accessories, and software compatibility. In many projects, moving from G120 to G220 should be managed as an engineered migration rather than a simple drive swap.

Should I Replace a Failed G120 or Upgrade to G220?

For an urgent failure with a short shutdown window, start by confirming a functionally validated G120 replacement. Evaluate G220 when the shutdown is planned and there is a defined reason for migration, such as new motor requirements, communication, diagnostics, security, safety, or power quality.

Can I Reuse a G120 Control Unit or Power Module With G220?

Do not plan on reusing G120 PM and CU components as though G220 were another modular combination within the same architecture. Record the complete existing configuration, then build a separate G220 BOM. Any reusable external component must be confirmed individually.

What Motor and Load Data Are Needed?

Provide motor voltage, rated current, power, speed, motor type, efficiency class, feedback device, speed range, load type, acceleration, overload duration, starts per hour, braking or regeneration needs, and motor cable length. Kilowatts or horsepower alone are not enough for a reliable drive selection.

How Do I Verify Communication Compatibility?

Check more than the protocol name. Confirm the drive communication module, PLC hardware configuration, telegram, GSD or GSDML file, device name, network address, I/O mapping, topology, diagnostic behavior, engineering software version, and firmware.

 

Plan for PLC testing even when both configurations use PROFINET or PROFIBUS.

Can the Existing Reactor, EMC Filter, or Braking Resistor Be Reused?

Only after checking the exact ratings and purpose. Verify voltage, current, power, thermal limits, connection method, switching conditions, approvals, and compatibility with the selected drive.

 

Treat the item as "not yet verified" until the current documentation or a qualified technical review confirms reuse.

Final Recommendation

For an urgent G120 failure, first verify a replacement that preserves the proven installation and minimizes changed variables.

For a planned retrofit, compare G120 continuation and G220 migration with the compatibility checklist, complete BOM, total installed cost, test plan, and rollback plan.

For a new project, select the platform from the motor, machine, customer, safety, connectivity, service, and lifecycle requirements.

The most reliable Siemens SINAMICS G120 vs G220 decision starts with exact order numbers and application data, not a family-level feature list.

Send your G120 part numbers and motor nameplate for a replacement or migration review, or request a Siemens VFD quote.

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