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About Us

DO Supply is a global automation parts reseller focused on hard-to-find and obsolete industrial automation products. Based out of Raleigh, NC, we service customers worldwide, providing excellent customer and sales support, as well as offering our top-of-the-line warranty on all parts sold.

What you can expect from DO Supply

Quality Products

Our products are rigorously tested and cleaned, backed by a 2-year DO Supply warranty.

Fast Shipping

We offer various shipping options from UPS, FedEx Priority Overnight, DHL and similar. We also ship internationally via DHL, FedEx, and UPS.

45+ Years Expertise

While other automation experts have some expertise, we have nearly half a century, allowing us to help you find the ideal replacement or repair solution.

Who is DO Supply?

We are a leading global supplier of industrial automation replacement parts, dedicated to providing expert support, speed, and reliability. We offer a huge inventory of need-it-now surplus PLCs, drives, motors, HMIs, and more. Trusted worldwide, we supply parts from 1981 to today by manufacturers such as Allen Bradley, GE, Eaton Cutler Hammer, Mitsubishi, Johnson Controls, and more. With an extensive inventory of surplus products, we are sure you will find what you are looking for. Our commitment to quality and service is reflected in our A+ Better Business Bureau rating. We guarantee prompt delivery and responsive support, empowering businesses to streamline operations and enhance productivity through reliable automation solutions

Replacements

We pride ourselves on being your need-it-now destination, specializing in immediate solutions for hard-to-find and obsolete replacements for PLCs, drives, motors, HMIs, and more.

Repairs

Save money with our repair service backed by a 2-year DO Supply warranty, serviced by US-based technicians.

Learn more

Dive deep into 40+ years of company history

Backed by multiple certifications

Our services

As industrial automation specialists, we focus on top brands like Allen Bradley, GE, Eaton Cutler Hammer, Mitsubishi, and Johnson Controls, sourcing hard-to-find and discontinued parts. Our dedicated team ensures quality through meticulous testing and repairs. With fast shipping and exceptional customer service, we offer a seamless experience. Plus, our in-house repair technicians provide repair services for most products.

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Get millions of automation parts delivered tomorrow.

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Repair

Get your automation parts repaired quickly.

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Sell

Turn unused automation equipment into cash.

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Testimonials

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Our facilities

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Latest updates from the experts

Discover insightful industry knowledge

19 October 2026

Understanding Torque Control vs. Speed Control in Industrial Applications

Speed control and torque control are the two main operating modes used by servo drives and variable frequency drives (VFDs) to run primary AC and DC electric motors. The drive’s internal control loops govern output voltage, current, and frequency based on the approach chosen under Torque Control vs. Speed Control system topologies. Torque control modulates active stator current to provide precise rotational force independent of speed variations, while speed control prioritizes maintaining the target shaft velocity regardless of load fluctuations. To implement the best control mode, we will analyze this article as Torque Control vs Speed Control, process stability, safety, and energy efficiency; system engineers must examine load characteristics, feedback devices, and mechanical dynamics. Order Allen-Bradley Servo Drive 1398s Here The motor drive operates as a closed-loop velocity regulator in speed control mode, with the inner torque reference being adjusted by the outer control loop...

16 October 2026

AC Drive Derating: When and Why It Matters

Sizing the right AC drive can be a bit complicated. After all, you’re met with motor nameplates to match, power supply considerations, and environmental parameters. Though for operations in hotter-than-normal temperatures, at high elevations, or even with single-phase power, things get even trickier. These conditions call for derating your AC drive. Derating an AC drive means lowering its maximum continuous current or output capacity below its nameplate rating due to environmental conditions, such as high temperature, elevated altitude, and phase conversion. Today we will walk you through when it’s appropriate to derate your AC drive and why it is beneficial. Derating an AC drive is important to keep the system optimized during operation in extreme conditions. It involves lowering your drive’s current or output in increments, depending on the severity of the condition. This will help protect the drive from overheating and extend its longevity at the sacrifice of performance. This...

14 October 2026

Common Causes of Intermittent Drive Faults That Aren’t the Drive

The most time-consuming diagnostic issue in industrial motor control is intermittent drive faults. Production halts, the drive trips, a technician resets it, and it runs for hours before malfunctioning again under similar circumstances. Since the drive is the most visible component and is showing the failure code, it is natural to blame it. Replacing the drive instantly restores production. The issue is that most persistent drive problems can be traced to external factors, such as loose power connections, deteriorated cable insulation, mechanical binding, supply voltage disruptions, or interference from control signals. A mechanical or electrical root cause, rather than a drive malfunction, often causes intermittent drive failure under the same circumstances. Effective drive fault research starts with understanding these external sources and the diagnostic methods that separate them. In industrial installations, loose connections are the second most common cause of drive faults. Heat...