What Is Sinamics? Siemens Drive Family Explained

You see the name on drives sitting in panels all over North American plants — Sinamics. But if you're new to a site or evaluating a spare, you may have questions: What is it exactly? How does it fit into the Siemens product universe? And what's a G120C worth on the market today? This guide answers all of it, plant-floor straight.

What Does "Sinamics" Mean?

The name is a Siemens portmanteau: "SIN" from Siemens, plus "AMICS" — a nod to dynamics. It replaced the older Simovert and Micromaster branding when Siemens unified its drive portfolio in the early 2000s. Today, Sinamics covers everything from fractional-horsepower cabinet drives to multi-megawatt central drives used in steel mills and paper lines.

The word "Siemens" itself dates back to Werner von Siemens, the German inventor and industrialist who founded the company in 1847. The SI unit of electrical conductance — the siemens (S) — is named after him. In plant automation, "Siemens" means one thing practically: the SIMATIC PLC and Sinamics drive ecosystem that runs a huge share of the world's industrial machinery.

Where Does Sinamics Fit in the Siemens Portfolio?

Siemens organizes its automation products under the SIMATIC umbrella for controllers, Sinamics for drives, and Simotics for motors. They're designed to integrate tightly — a SIMATIC S7-1200 or S7-1500 PLC talking to a Sinamics G120 over PROFINET is a very common architecture in new panel builds.

The Sinamics Family — Which Letter Means What?

The letter prefix in every Sinamics model number tells you the application class:

What Is the Sinamics G120 — and What Makes the G120C Different?

The G120 is Siemens' workhorse general-purpose drive. It's a modular system: a Power Module (PM) clips onto a Control Unit (CU) — you mix and match. That modularity is useful in large installations. Swap out a blown power module without touching the control unit or its parameters.

The G120C is the compact, integrated version. Power module and control unit are one piece. That means:

• Smaller panel footprint — good when space is tight
• Fewer connection points — faster install
• Lower cost per unit at small power ranges
• Less flexibility — you replace the whole drive if either section fails

What Is the Price of a Sinamics G120C?

New G120C pricing from distribution varies widely based on power class, voltage rating, and the fieldbus option built into the control unit (PROFINET, PROFIBUS, USS/Modbus). Smaller, lower-power units cost considerably less than larger frame sizes. New list prices from Siemens distribution for mid-range units can run into the hundreds to low thousands of dollars depending on configuration.

Surplus and tested-used pricing is often 40–70% below new list — which is why maintenance departments regularly source G120C units from reputable surplus suppliers, especially when a machine is older and a quick turnaround matters more than a full OEM warranty.

What Are Siemens Drives Used For?

Practically every industry that runs a motor uses them. Common applications you'll find Sinamics drives controlling:

• Water/wastewater: pump speed control for pressure management and energy savings
• HVAC: fan and chiller pump drives in commercial and industrial buildings
• Food and beverage: conveyor lines, mixers, filling machines
• Oil and gas: compressor control, injection pump drives
• Automotive: assembly line conveyors, test stands
• Printing and packaging: web tension control, servo positioning

The core job is always the same: control motor speed and torque more precisely than a direct-on-line starter ever could, while saving energy by matching motor output to actual process demand.

How Does Sinamics Communicate With a PLC?

Sinamics drives support multiple fieldbus options depending on the control unit variant:

• PROFINET — Siemens' Ethernet-based network. Native to SIMATIC S7 PLCs. Fastest and most capable for diagnostics.
• PROFIBUS DP — legacy but still extremely common. Millions of G120/G120C units run on PROFIBUS in the field.
• USS / Modbus RTU — serial protocols. Common for third-party PLC integration or simple speed reference setpoint via RS-485.

The control unit variant you order determines which fieldbus you get. You cannot field-convert a PROFIBUS CU to PROFINET without changing the control unit entirely. This is a critical point when sourcing a replacement.

Common Problems and What They Usually Mean

• Drive won't power on / no display: Check 24VDC control supply on terminals. Blown fuse or failed SMPS is common after a voltage spike.
• DC bus or IGBT fault on display: Often caused by a failed IGBT or a motor winding fault reflecting back into the drive. Isolate the motor first and test the drive on a known-good load. Look up the exact fault code displayed against the Siemens fault list for your specific CU firmware version.
• Drive runs but motor overheats: V/Hz profile mismatch, motor nameplate data entered incorrectly in parameter set, or motor winding degradation. Run the motor ID routine (Quick Commissioning) if you haven't.
• Fieldbus communication loss fault: Check cable seating, PROFINET IP address conflicts, or PROFIBUS address DIP switches. A replacement drive must have the same bus address and GSD/GSDML file loaded in the PLC project. Confirm the exact fault code displayed against your CU firmware documentation.
• Operator panel shows "- - - -": Usually means the drive is in remote control mode and is waiting for a run command from the fieldbus. Not a fault — just a mode state.

When Replacement Makes More Sense Than Repair

Sinamics drives are repairable — Siemens and third-party repair shops handle board-level work. But repair turnaround time on a production-critical machine can be measured in weeks. Here's when buying a tested replacement unit makes more financial sense:

• The machine has a single-drive bottleneck — every hour down costs more than the drive
• The failed unit is more than 8–10 years old — repair cost approaches replacement cost
• You need a spare on the shelf and don't want to tie up capital in new list-price stock
• The OEM lead time for new units is extended (this has been a recurring issue in recent years)

Further Reading

For official documentation, Siemens maintains a full literature and support portal. You can search for G120C manuals, GSD files, and firmware release notes directly at support.industry.siemens.com. Always match the manual version to the firmware version stamped on your drive nameplate.

Disclaimer: This guide is provided for general information only. Procedures vary by model, series, and firmware version. Industrial equipment can cause serious injury, equipment damage, or downtime if serviced incorrectly. Always consult the manufacturer's official documentation and a qualified professional before performing work, and follow your facility's lockout/tagout and safety procedures. PLC Department is an independent surplus supplier and is not affiliated with or endorsed by the manufacturers referenced. Use this information at your own discretion.