What Is Electro-Hydraulic Control in Industrial Automation?

No one ever said industrial automation was simple—electro-hydraulics certainly aren’t. However, learning how to control them is essential for automation.

Industrial automation is a field with tons of different processes and technologies—one of the most useful of which is electro-hydraulics. While this concept is fascinating on its own, electro-hydraulics are useless without a way to control them. We’re going to dive deeper into electro-hydraulic control in industrial automation, as well as take a look at how electro-hydraulics are useful in a variety of facilities and applications.

Breaking It Down: Electro

Before we describe electro-hydraulics as a whole, it’s important to have a basic understanding of the concepts that make up the process. The “electro” part of the word refers to the electrical portion of the process. In the case of electro-hydraulics, this electricity is used to send signals to various parts of the drive in order to instruct other areas to carry out given tasks.

Breaking It Down: Hydraulic

The other half of electro-hydraulics are the hydraulics, a mechanical function that produces movement through liquid pressure. Hydraulic systems contain different actuators, irrigation systems, aqueducts, and hoses, depending on the function of the given system. You’ll most commonly see hydraulics show up in automotive braking and power steering, but it’s an essential function in industrial automation, too.

When we’re discussing electro-hydraulics, this part of the system is used for its adjustable hydraulic valves that open and close.

The Electro-Hydraulic Control Process

When we put those unique halves together, we gain a better understanding of how the entire electro-hydraulic process works. Through the use of a solenoid (which is a coil of wire, a moveable plunger, and a housing), electrical energy is converted to mechanical energy that can open, close, or change the direction of liquid flow in a directional valve.

Electrical signals are sent to the solenoid, directing it to open, close, or change direction. Also at work in the valve are chambers known as ports. When the solenoid slides a spool inside the valve, different ports open or close. When liquid is blocked or allowed to flow, you can achieve different mechanical results in your system.

All of this would not be possible without signal processing, which is done through electrical signals on a computer. When you have continuously adjustable valves and proportional valves, you can constantly adjust set points for increased process compensation.

Upgrading Hydraulic Systems

Electro-hydraulic actuators are an improvement over basic hydraulic systems. Basic hydraulic systems require multiple hydraulic pumps and tubing, while electro-hydraulic actuators include a pump of their own. This makes system design simpler while also increasing the reliability and safety of your overall system.

Benefits of Using Electro-Hydraulic Control

Now that you have a solid understanding of the inner workings of an electro-hydraulic system, let’s explore the benefits of using one in your facility or industry. For one thing, the efficiency upgrade from traditional hydraulic systems is substantial. Depending on what you will use your electro-hydraulic system for, you may be able to see an increase in efficiency of up to 80 percent.

The reason for this sweeping change is the electro-hydraulic motor’s power-on-demand capabilities. Your motor will use no energy when it is not specifically needed, which can significantly reduce the amount of energy waste in your facility. This leads to a secondary benefit in the form of an increased component lifespan. When you don’t need to think about the engine and pump idling, bearings and seals will naturally last longer.

One other major benefit is the simplicity of the pump controls. Because of its unique design, signals only need to tell the pump information about speed and motor direction, as opposed to multiple proportional and directional values. Reduced complexity means that addressing problems when things go wrong becomes a much simpler situation.

Electro-hydraulic actuators can additionally be used in some instances that surpass the capacity of traditional hydraulics, as they can handle up to a 4,800-pound load. Despite this increased capacity, electro-hydraulic actuators are quieter than traditional hydraulic actuators, which may be an additional benefit in certain situations.

Finally, the size and availability of electro-hydraulic motors is a large advantage. Because these require a high-energy battery pack as opposed to a gas engine, an electro-hydraulic unit has far more versatility. When engineers don’t need to place a given component near others, it affords them greater design creativity and leads to a better final product.

Thankfully, the price of these units is also falling as more and more companies begin to develop parts and components. For instance, we have all the parts you need for the Mark V DS200 in stock now.

Drawbacks of Using Electro-Hydraulic Control

Of course, no technology is without its share of drawbacks. We want to make sure you understand the full picture of the technology you’re using before you make a decision. One of the biggest problems with electro-hydraulics is their perception. It was only a few short years ago that these devices were avoided because they caused more problems than they solved.

Upon their first introduction, electro-hydraulic actuators were much weaker and more unreliable than traditional hydraulic actuators. In the ensuing years, they have grown far more powerful and more dependable than traditional actuators.

However, electro-hydraulic actuators do still carry a higher upfront cost than their traditional counterparts. You’ll feel this financial factor more when you need to install multiple units, but it’s important to note that this is a high initial cost. In time, through efficiency savings and maintenance savings, electro-hydraulic actuators become good value and pay off.

The other issue is that while electro-hydraulic actuators come with reduced maintenance, that doesn’t mean they require nomaintenance at all. When something goes wrong, it’s important to have a specialist that can come in and fix the problem, as your average repair worker will likely be unable to address the issue.

Now that you know what electro-hydraulic control in industrial automation is, remember that AX Control can help you find the parts you need for your electro-hydraulic control system or any number of other industrial machines! We always provide competitive quotes on parts and repairs, so be sure to check with us first when you need parts for industrial automation. Contact our team today to learn more!

What Is Electro-Hydraulic Control in Industrial Automation?

Gas Turbine Maintenance Strategies To Consider

No matter what kind of gas turbine you use in your facility, there are a few core maintenance strategies that you should consider. Read on to learn more.

Many gas turbines are constantly at work in different facilities, but the maintenance strategies for keeping them up and running are largely the same. We’ve made a list of a few gas turbine maintenance strategies to consider to help your facility thrive.

Understand Your Assets

This might be an obvious suggestion, but make sure you know what you’re working with! Having a clear understanding of your current assets and procedures is essential to setting up a viable strategy. If you haven’t put pen to paper yet for your strategy, make that a priority. You can work out the gaps and kinks after writing everything down.

Prioritize Proactivity

Proactive maintenance is everything in an industrial environment. For gas turbines, you can avoid unnecessary downtime by fixing problems before they arise through condition-based maintenance. You’ll see many touting the benefits of time-based maintenance, but condition-based maintenance is more effective.

Time-based maintenance may cause you to replace components before they’ve worn down, meaning you’re wasting hours of use. When you change out parts based on condition, you know you’re getting the most out of them before replacements.

Determine Your Optimum Maintenance Process

Just as optimum organizational processes exist, optimum maintenance processes also exist. Collect data on your gas turbine in order to determine how to optimize these processes, like condition-based maintenance. You won’t know exactly the right time to replace a component until you can see your turbine’s performance data, with components showing varying degrees of wear.

Once you know the prime time for replacements, you can purchase components like the Mark IV DS3800 gas turbine control system to avoid extended downtime.

Now that you know these gas turbine maintenance strategies to consider, implement them at your organization. You’ll be surprised how much something like preventative maintenance can do for productivity in your facility!

The Difference Between DC & AC Drives in Automation

You can’t have success in the automation industry without DC or AC drives. Learn more about each type of drive and what makes them different in this guide.

Electrical motors are essential in automation, but they aren’t nearly as useful without a drive to regulate speed. Alternating current and direct current drives are crucial to the performance of motion control systems, but each tackles its job in a different way. Keep reading to discover the difference between DC and AC drives in automation and learn which is better for you.

Electrical Drives

AC and DC drives are both types of electrical drives—an electronic device that controls the speed of an electric motor. You would be hard-pressed to find an industrial facility without dozens of electrical drives employed across devices, as these are a critical component in every facility.

What Is an AC Drive?

AC drives are devices that control the speed of an AC motor—these motors can be used in a variety of applications, from controlling fans to operating complicated machinery.

To understand what AC drives do, it’s important to first have an understanding of AC motors. Alternating current motors typically have two or three phases that determine the number of electromagnetic coils inside.

In a two-phase motor, you’ll see two pairs of electromagnetic coils across from each other that form a plus shape. In the center of these coils (which are known as stators), there is a magnet, called a rotor. The stators function 90 degrees out of phase, and this discrepancy causes the magnet to rotate. A three-phase motor functions in much the same way but features three pairs of stators that are 120 degrees out of phase.

An AC drive system has three important parts: an operator control, a drive controller, and an AC motor. The operator control is the method for starting and stopping the motor, as well as changing the operating speed.

The drive controller works by changing a constant AC voltage and frequency into variable voltage and frequency.

Types of AC Controllers

Not all AC controllers are created equal. Let’s look at a few common types of AC controllers you’re likely to run into.

Pulse-Width Modulated

Pulse-width modulated AC controllers are among the most common in general-purpose drives. PWM controllers use a full-wave rectifier to convert the AC power source into a fixed DC voltage. A filter network then smooths the DC voltage and sends it through a pulse-width modulated inverter by use of high-power transistors.

This voltage is not truly sinusoidal but is instead a pulsed approximation—this is where the device gets its name. The waveform is pulse-width modulated, although it closely follows the regular shape of a sine wave.

Load Commutated Inverter

A load commutated inverter (LCI) is a system containing both an input and output thyristor bridge. The input bridge supplies a DC current into an inductor, while the output bridge passes the DC current to the generator’s stator, causing rotation.

What Is a DC Drive?

DC drives come with the same main parts as an AC drive; the operator control and drive controller are, in theory, the same components. However, a DC drive has a DC motor rather than an AC motor. As with an AC drive, the operator controller dictates the speed of the motor using a device like a dial.

The drive controller regulates the input using a phase control device or pulse-width modulator.

Types of DC Drives

Just as there are multiple types of AC controllers, there are several types of DC drives.


Most DC drives are nonregenerative, meaning they control torque and speed in a single direction. When you add another electromechanical armature, you can reverse polarity and change the direction of rotation.


Regenerative drives can control motor speed, direction of rotation, and torque. When the motor is braking, a regenerative drive can convert mechanical energy into electrical energy and return it to the AC power source. These are less common than nonregenerative drives but have significant power-saving advantages.

Key Differences

Now that you know a bit more about how AC and DC drives work, let’s explore the key differences between the two.


As we explored earlier, the main difference between these drives is the way they operate. While AC drives convert AC voltage into DC with a rectifier circuit, DC drives convert the AC input into DC at varying voltages. While the processes are different, the result is the same: motor speed control.


A major difference between the two drives is that DC drives are self-starting while AC drives are not. This is a benefit that pushes DC over the edge for many people—a quick start is always a positive!

Speed Limitations

The commutator in DC drives limits the maximum speed, while AC drives do not share this limitation. Two-pole AC drives can reach 3,600 rpm at 60 Hz, while four-pole AC drives reach approximately 1,800 rpm.

Converter Circuit

AC drives require two converter circuits: one to convert AC to DC and an inverter to convert DC back to AC. DC drives only require one converter circuit—the rectifier that allows AC to DC conversion.


Because they utilize two conversions, AC drives are considered more complex than DC drives. This allows for easier repair of DC drives, which may save you time on the factory floor.


Due to the simplicity of their design, DC drives are generally less expensive than AC drives. Repairing or replacing a DC drive will typically cost less than AC drive maintenance.

When you need local or remote operator controls for power modules, there isn’t a better choice than the Reliance FlexPak 3000. It’s a DC drive line that’s ideal for configured drive applications in which you require as much wiring and panel flexibility as possible.

Now that you know the difference between DC and AC drives in automation, you can choose which is best for you based on your applications. When you require a more efficient option, you may want to choose DC power. LED lights, for example, are far more efficient than incandescent lights, and a majority of LEDs utilize DC power. If you have any questions about the differences between these two types of drives, contact the experts at AX Control.

The Difference Between DC & AC Drives in Automation