3 Phase Hydraulic Power Pack—The Ultimate Guide

From the continuous operation of industrial machinery to the demand for unmanned automated production lines, the 3 phase hydraulic power pack has always been a reliable equipment. Without the need for cumbersome assembly, and without frequent maintenance, it enables your hydraulic equipment to enhance production efficiency from the source of power.

What is 3 Phase Hydraulic Power Pack?

The 3 phase hydraulic power pack is a modular power unit that integrates the core components of hydraulic transmission and is powered by three-phase AC. Its core function is to provide stable hydraulic energy for hydraulic actuators such as cylinders and motors. It is not a single device. It pre-installs and integrates key components such as three-phase asynchronous motors, hydraulic pumps, hydraulic oil tanks, valve group, and filters into an independent unit. Therefore, users do not need to build a separate and decentralized system, which can greatly simplify installation and commissioning.

Composition

Three-Phase Asynchronous Motor – Power Input

The 3 phase hydraulic power pack is the core energy source of the three-phase asynchronous motor. It can convert three-phase alternating current into mechanical energy to drive the hydraulic pump. Through the output shaft, it is directly rigidly connected or connected with the hydraulic pump through a coupling to drive the pump to stably complete the oil suction and oil pressure actions, providing continuous power support for the entire hydraulic system.

In terms of compatibility, it needs to match industrial standard three-phase alternating current, with common specifications being 380V/50Hz and 480V/60Hz. The power range covers a wide spectrum from 1.5kW to 75kW, and can be adapted to different load scenarios as needed.

Hydraulic Pump – Energy Conversion

Driven by an electric motor, the hydraulic pump utilizes the rotational motion of its internal rotors or gears to expand the suction chamber volume, creating a vacuum that draws hydraulic fluid from the reservoir. Subsequently, the compression chamber volume decreases, squeezing and pressurizing the fluid. Finally, the high-pressure oil is delivered to downstream valve assemblies, powering hydraulic actuators.

In practical applications, hydraulic pumps are commonly categorized into three types.

Gear Pump: Operates by squeezing fluid through dual gear meshing, suitable for low-pressure applications ≤16MPa. It delivers moderate flow with significant pulsation but offers low cost and simple structure.

Vane Pump: Achieves suction and pressure by a rotor driving vanes to slide along a stator, applicable for medium-pressure scenarios ≤25MPa. It provides stable flow and low operational noise.

Hydraulic Piston Pump: Utilizes reciprocating piston motion to squeeze fluid, capable of withstanding high pressures ≤31.5MPa. It delivers high flow rates and exhibits high energy conversion efficiency.

Hydraulic Valve Group

Hydraulic valve group is a critical component for regulating hydraulic system operation and ensuring safety. It primarily controls the pressure, flow rate, and direction of hydraulic fluid with precision while preventing system overload. Typically integrated into a single valve block, it features a compact structure.

Relief valve (safety valve): Serving as the first line of defense for system pressure protection, it automatically opens when oil circuit pressure exceeds the set value, diverting excess fluid back to the reservoir. This prevents damage to pumps, valves, and actuators caused by high pressure. Certain models support manual pressure adjustment to accommodate varying load conditions.

Check Valve: Prevents backflow, shielding the hydraulic pump from reverse oil impact when the motor stops to avoid pump damage.

Throttle Valve and Flow Control Valve: Throttle valves regulate oil flow to adjust actuator speed but are significantly affected by pressure fluctuations. Flow control valves maintain stable flow through pressure compensation, making them ideal for applications demanding high precision in speed control.

Auxiliary Support Components

Hydraulic Oil Tank

It can store sufficient hydraulic oil and also dissipate the heat generated by the pressurized hydraulic oil, preventing the oil temperature from rising too high and causing the oil to deteriorate or the seals to age.

A liquid level gauge will be placed inside the tank for easy oil level monitoring. An air filter will be installed at the fueling port to prevent dust from entering during refueling. A drain valve is set at the bottom of the tank to facilitate the emptying of old oil during the replacement of hydraulic oil.

The inner wall of the tank is usually treated for rust prevention, such as galvanization or powder coating, to avoid metal rusting and contamination of the oil.

Hydraulic Filter

It can filter impurities in the hydraulic oil, protecting the pumps, valves and other precision components. These components have extremely small clearance, and impurities can easily cause jamming or wear.

Oil Suction Filter: It is usually installed at the suction port of the pump, with a lower filtration accuracy (usually 80-180 μm), mainly to prevent large particles from entering the pump.

Return oil filter: It is installed in the pipeline from the actuator’s return oil to the oil tank, with a higher filtration accuracy (usually 10-50 μm). It is used to filter impurities in the used oil to prevent circulation pollution.

Cooler

When the power unit works at full load for a long time, the oil tank alone cannot control the oil temperature. The cooler uses forced heat exchange to lower the oil temperature and ensure the performance of the oil and the lifespan of the seals.

Air-cooled type: It cools the oil in the oil circuit by blowing air over the heat sink.

Water-cooled type: It cools the oil by exchanging heat with the oil through water. The cooling efficiency is high.

Operating Principle

The core essence of the 3 phase hydraulic power pack is energy conversion and transmission. Its working principle revolves around the closed-loop conversion of 3-phase electrical energy → mechanical kinetic energy → hydraulic potential energy → mechanical working energy.

Electrical Energy → Mechanical Kinetic Energy

After 3-phase alternating current is connected to the electrical control box, it is supplied to the stator winding of the motor through circuit breakers and AC contactors, generating a rotating magnetic field. The magnetic field drives the rotor to rotate, directly converting the electrical energy into the mechanical kinetic energy of the motor output shaft.

The 120° phase difference characteristic of the 3-phase electricity ensures stable and undisturbed torque from the motor, along with high power density, providing continuous and powerful driving force for the subsequent hydraulic pump.

Mechanical Kinetic Energy → Hydraulic Potential Energy

The motor output shaft rotates synchronously with the input shaft of the hydraulic pump through a coupling, driving the moving parts inside the pump and causing the volume of the suction chamber to increase, creating negative pressure. The hydraulic oil in the oil tank is drawn into the suction chamber under the action of atmospheric pressure through the suction filter. Subsequently, the volume of the pressure oil chamber of the pump decreases, and the oil is compressed mechanically to be pressurized, converting into specific pressure and flow rate of hydraulic potential energy, namely high-pressure oil.

Control of Hydraulic Potential Energy’s Pressure, Flow Rate and Direction

The high-pressure oil flows through the relief valve to regulate pressure, the throttle valve to regulate flow, and control speed. Some hydraulic power packs contain a reversing valve, which can switch the oil path direction to drive the opposite action.

Hydraulic Potential Energy → Mechanical Working Energy

The high-pressure oil regulated by the valve group is transported through high-pressure pipelines and quick couplings to external actuators: oil cylinders, hydraulic motors.

If it is an oil cylinder: The high-pressure oil pushes the piston to move along the cylinder barrel, converting the hydraulic potential energy into linear thrust or pull.

If it is a hydraulic motor: The high-pressure oil drives the rotor of the motor to rotate, converting the hydraulic potential energy into rotational torque.

This ultimately completes the conversion of hydraulic power → actual working action.

Oil Circulation and System Protection

After the actuator completes the action, the low-pressure oil returns to the oil tank of the power pack through the return oil pipeline. During the return process, filtration and cooling will be carried out. Finally, the purified and cooled oil fluid re-enters the suction port, forming an oil fluid closed-loop circulation.

Type

According to the Type of Hydraulic Pump

The hydraulic pump is the core component for energy conversion in the 3 phase hydraulic power pack. Classifying the 3 phase hydraulic power pack based on the type of hydraulic pump is the most crucial dimension for categorization. You will find that he type of the hydraulic pump directly determines the pressure level, flow characteristics, efficiency, and cost of the hydraulic power pack.

3 Phase Hydraulic Power Pack with Gear Pump

It uses a gear pump, which squeezes the oil through the meshing of two gears. The structure is the simplest. It has low cost, low failure rate, no complex moving parts, and simple maintenance. However, the flow pulsation is relatively large, and the operating noise is slightly higher. Due to the large gear gap, it is not prone to jamming, so it has strong anti-pollution ability.

3 Phase Hydraulic Power Pack with Vane Pump

The vane pump drives the vanes to slide along the stator through the rotor, and completes the oil suction and pressure application actions by utilizing volume changes. The notable advantage of this type of power unit lies in its stable flow, low pulsation, and low operating noise. The pressure is at a moderate level, and the energy conversion efficiency is also higher than that of the gear pump. However, due to the small gap between the vanes and the stator, it is prone to get stuck by impurities in the oil, so it requires higher oil cleanliness. Therefore, it is more suitable for medium-pressure scenarios that demand stable operation and low noise.

3 Phase Hydraulic Power Pack with Piston Pump

The plunger pump squeezes the oil through the reciprocating motion of the plunger, achieving energy conversion by means of the maximum volumetric change rate. The core advantage of this type of power unit lies in its strongest power output, which can stably provide high pressure and large flow. Its energy conversion efficiency is the highest among various pump types, with low energy loss. It can withstand full-load operation for a long time and can meet the continuous operation requirements of heavy-duty equipment.

However, the structure of the plunger pump is relatively complex, resulting in a higher overall cost. At the same time, the clearance between the plunger and the cylinder body is extremely small. If impurities are mixed in the oil, it is prone to cause jamming faults. Therefore, extremely high cleanliness of the oil is required, and a high-precision filtration system must be used in conjunction.

According to Structure and Installation Method

Vertical 3 Phase Hydraulic Power Pack

The vertical three-phase hydraulic power unit features a structure where the motor and hydraulic pump are arranged vertically, with the motor positioned above and the pump below. The pump shaft extends vertically into the oil tank, and the accompanying tank is typically designed as a vertical cylindrical unit.

The core advantage of this power unit lies in its compact footprint, maximizing horizontal space efficiency. However, due to the structural limitations of the vertical cylindrical tank, its heat dissipation surface area is relatively small. Careful consideration of heat dissipation measures is required to control oil temperature.

Horizontal 3 Phase Hydraulic Power Pack

The motor and hydraulic pump of the horizontal three-phase hydraulic power pack are arranged horizontally, with their axes kept parallel. Power is precisely and stably transmitted through a coupling. The matching oil tank adopts a horizontal rectangular design and is directly placed flat on the ground, forming an integrated layout with the motor and pump unit. It has a low center of gravity, stable operation, a large oil tank capacity, and good heat dissipation. Due to the horizontal layout, it is easy to operate and convenient to disassemble the pump and valve unit during maintenance.

Compared with the Single Phase Hydraulic Power Pack

The 3 phase hydraulic power pack is also a commonly used power unit. The core difference between the 3 phase hydraulic power pack and the single phase hydraulic power pack lies in the fundamental nature of their power sources, which further extends to key dimensions such as power, pressure, stability, and applicable scenarios.

Power Source Characteristics

The 3 phase hydraulic power pack uses three-phase alternating current (380V/50Hz, 480V/60Hz) as the power source. The phase difference of the three-phase current is 120°, and the current output is continuous and uninterrupted, which can avoid power fluctuations. However, its power supply requires industrial-specific wiring.

The single phase hydraulic power pack relies on single-phase alternating current (220V/50Hz, 110V/60Hz). It has only one phase, and the current output has zero-crossing points, resulting in obvious power pulsation. It uses civilian electricity and has convenient power supply.

Core Performance Parameters

3 phase hydraulic power pack: Power ranging from 1.5kW to 75kW (customized models can reach up to 100kW), pressure ranging from low to high, flow rate 5-150L/min, continuous torque without pulsation, and no jamming of the actuator.

Single-phase hydraulic power unit: Power ≤ 3kW (maximum 5kW), can only operate at low pressure, flow rate 1 – 20L/min, torque has pulsation, the actuator is prone to slight jamming.

Core Component Configuration

The 3 phase hydraulic power pack is equipped with a three-phase asynchronous motor. It has a small starting current and low working heat, and the energy conversion efficiency can reach 85% – 95%. The hydraulic pump selection is flexible. You can combine it with gear pumps, vane pumps or piston pumps according to your needs. The accessory configuration is rich, and most of them are equipped with coolers, dual filters for oil intake and return, and complex valve groups that can control pressure, flow and direction, providing comprehensive functions.

The single-phase hydraulic power unit uses a single-phase asynchronous motor. It has a large starting current and high working heat, with an efficiency of only 75% – 85%. The hydraulic pump can only be selected as a gear pump. The additional component configuration is simple, without a cooler, only equipped with a single suction oil filter, and the valve group can only achieve basic pressure protection, with relatively simple functions.

Advantages

The Power Output is Stable without Fluctuations

Based on three-phase alternating current with a 120° phase difference characteristic, the three-phase asynchronous motor outputs torque continuously without pulsation, which can avoid the power fluctuations caused by voltage fluctuations in single-phase motors.

High Power Density and Strong Load Capacity

Under the same volume, the output power of the three-phase asynchronous motor is 2-3 times that of the single-phase motor. When paired with a high-pressure hydraulic pump, it can achieve a high-pressure output of 10-31.5 MPa, meeting the requirements of heavy-load equipment.

Precise Control of Pressure and Flow

The integrated relief valve can precisely limit the maximum pressure (error ≤ 0.5 MPa), avoiding equipment damage due to overpressure. The throttle valve or variable pump can achieve stepless flow adjustment, which can control the speed of the actuator and adapt to complex working conditions such as fast advance – slow pressure – fast retreat.

Easy Installation

The core components have all been pre-installed and debugged in the factory. Users do not need to design the brackets or pipelines separately. They only need to fix the power unit, connect the three-phase electricity and the oil pipe of the actuator, and the installation can be completed within 1-2 hours.

Save Space

Integrated design reduces the volume of the power unit to only 1/3 – 1/2 of that of traditional decentralized systems. The vertical model occupies only 0.2 – 0.5 square meters of space, and the compact type can even be reduced to 0.1 square meters, making it suitable for narrow spaces.

Built-in Pipelines Reduce Failure Points

In traditional systems, exposed pipelines are prone to leakage due to collisions or aging. However, the key pipelines of the three-phase power unit are mostly built inside the valve block or oil tank, with only the oil outlet and the actuator exposed, reducing the leakage risk by more than 80%, thereby reducing oil waste and equipment downtime.

How to Choose the 3 Phase Hydraulic Power Pack？

Select the Type of Hydraulic Pump

You need to choose the pump type based on the pressure and flow requirements. For low pressure (≤10MPa) and low precision scenarios, choose a gear pump as it is cost-effective and has strong anti-pollution capabilities. For medium pressure (10-20MPa) and scenarios requiring low noise and stable flow, choose a vane pump. For high pressure (≥16MPa) and heavy-duty high-flow scenarios, you must choose a piston pump as it has strong resistance to high pressure and loads. Avoid using a small pump to handle a large load or a large pump to handle a small load to prevent failures or cost waste.

Match the Working Environment

You need to adjust the power unit structure and protection according to the operating environment. For normal temperature use, select the ordinary model. For high temperatures (≥40℃), a cooler is required; for low temperatures (≤0℃), an oil tank heating rod + low pour point oil is needed.

For construction sites with a lot of dust, select an IP54 or higher protection electrical control box. For humid environments, choose a waterproof model with IP55/IP65 protection.

For narrow spaces, select a vertical type. For high vibration scenarios, choose an enhanced frame + elastic coupling to buffer vibrations and protect components.

According to the Control Requirements

You also need to configure control functions based on operational accuracy and automation requirements. Only the basic type with start-stop + pressure protection is selected, equipped with an overflow valve + ordinary electrical control box. If you need to adjust the flow rate and speed, install a throttle valve, speed control valve, or variable pump. If the actuator needs to perform forward and reverse actions, add a reversing valve.

Application Fields

Industrial Machinery Field

Industrial machinery is the most important application field for 3 phase hydraulic power packs, covering metal processing, plastic molding, general manufacturing, etc. The core requirements are stable pressure, flow control, low failure rate, and compatibility with continuous production line operation.

In metal processing machinery, hydraulic presses use high pressure to push the slider down to complete metal stamping, forging, and bearing press-fitting operations. Bending machines and shearing machines rely on hydraulic drive for the mold to achieve bending or cutting of metal sheets. These devices require extremely high pressure, the downward speed of the slider can be quickly switched, and the load impact is large.

Selecting a 3 phase hydraulic power pack of piston pump type can meet high pressure and heavy load requirements, and achieve precise speed control by combining variable pump + throttle valve. Built-in relief valve and pressure relay, when the pressurization exceeds the limit, it automatically releases pressure to protect the pump valve, and is suitable for such equipment.

Construction Machinery Field

In the field of construction machinery, the 3 phase hydraulic power pack provides stable power support for a variety of core equipment. For instance, hydraulic forklifts use hydraulic power to lift and lower the forks, facilitating the loading, unloading, and transportation of goods. Mobile hydraulic lifting platforms utilize hydraulic power to vertically ascend the platform, safely meeting the requirements for high-altitude maintenance, material hoisting, and other high-altitude operations.

Automation Production Line Field

In automotive manufacturing, welding fixtures use hydraulic clamping to fix body parts. Assembly and press-fitting use hydraulic to press bearings and sleeves onto automotive components; conveyor rollers use hydraulic motors to drive and achieve workpiece transportation.

Logistics and Warehousing Field

Hydraulic stacker cranes use hydraulic drive to lift the forks to store goods in high-level shelves. Palletizing platform lifts use hydraulic drive to lift the platform to achieve inter-level transportation of goods. Hydraulic boarding bridges use hydraulic drive to lift the landing pad, connecting the truck and the warehouse floor, facilitating forklift loading and unloading of goods. Container loading and unloading platforms use hydraulic drive to tilt the platform to unload goods inside the container quickly.

Conclusion

The 3 phase hydraulic power pack is the core equipment for stabilizing the energy supply and enhancing production efficiency in industrial hydraulic systems. Regardless of the type, they provide standardized power support for hydraulic equipment of various scales through continuous and pulsation-free power output, precise pressure and flow control, and integrated convenient operation. Choosing the right 3 phase hydraulic power pack not only reduces energy consumption and maintenance costs, but also strengthens production stability and provides solid power support for your production activities.