vfd hydraulic pump price

A hydraulic power unit (HPU) is a common product that IFP supplies to its customers for all types of hydraulic applications.  Most customers order their HPUs with standard electric motors and across-the-line motor starters.  These electric motors spin at a constant RPM.  Because the electric motor spins at a constant RPM, the hydraulic pump coupled to the motor is constantly flowing oil and is likely wasting energy in between system operations.

By allowing the VFD controlled HPU to match the system pressure and flow requirements by varying the pump speed, there are several other advantages to using these VFD controlled HPU systems.  By reducing energy put into the system, less heat is generated that has to be dissipated by the system.  There are typically noise reductions with VFD controlled HPUs.  With reduced heat and reduced system shock, this typically leads to longer component life depending on the load cycle.  Hi-lo systems can now be completed with just one fixed displacement hydraulic pump.  By over-speeding the pump for extra volumes of fluid, the VFD controlled system does not need a low pressure/high flow pump along with the high pressure/low flow pump.  Charging an accumulator can become more efficient as well.  Once the accumulator is charged, the VFD controlled HPU can slow down the flow output of the hydraulic pump and maintain the system.  Unloading the pump for accumulator charging is typically done with extra valves and consuming unnecessary energy.  Overall costs of hydraulic systems can be reduced because smaller hydraulic pumps can be used, less valves are required, less or no cooling for heat dissipation, and smaller reservoirs can be used.

The applications are endless for VFD controlled HPU systems.  These systems can be used on anything from a simple filter and lubrication system to extremely complex test stands and presses.  With increased efficiency and control, VFD controlled HPU systems will become more common in industry.

For more information on how you can utilize Drives and VFD controlled HPUs, please contact us here to receive a personalized contact by an IFP Application Engineer:

At NPE2018, both Jomar Corp., Egg Harbor Township, N.J., and Bosch Rexroth Corp., Bethlehem, Pa., introduced new products that provide an educational illustration of the differences between two types of energy-saving variable-speed drives for hydraulic pumps.

The term “servo-hydraulic” has gained currency to describe new generations of plastics machinery that utilize hydraulic pumps but with energy savings and noise reduction closely approaching those obtained with all-electric servo motors and drives. At the same time, popularity has also been growing for aftermarket retrofits of conventional hydraulics with variable-frequency drives (VFDs), another way of saving energy by varying pump speed—even to zero—according to the instantaneous load demand of the system.

Bosch Rexroth introduced at the show its Sytronix DRn 5020 VFD, aimed specifically for converting variable-displacement hydraulic pumps driven by conventional fixed-speed (1800 rpm) motors to quieter, more energy-efficient variable-speed operation. It reportedly saves up to 75% in electrical energy for systems that have long dwell times; and the average noise reduction is 8 to 10 dBa vs. fixed-speed hydraulic drives. This “intelligent” drive senses the motor torque and pump pressure to calculate the pump displacement, or position of the swash plate, to keep it in the most efficient position for the real-time load requirement. This drive is Industry 4.0 compatible, as it adds operating data collection and digital communications to conventional electric motors and hydraulic pumps that normally do not have these capabilities.

Bosch Rexroth notes that VFDs are considerably less expensive than servo drives, but the firm also points out in a white paper that they provide less tight control over motor speed than servos and have lower dynamic performance—ability to respond and control pressure/velocity changes. VFD drives are thus more suited to steady or slowly changing loads. They also have low-speed limitations and are usable only to 400-500 rpm.

Bosch Rexroth points to an instructive use of both its MSK servo motor and the new Sytronix DRn 5020 on Jomar’s new IntelliDrive injection-blow molding machines. Jomar often refers to these machines as “servo-hydraulic,” but the servo drives only the hydraulic pump for the injection unit. The injection and blowing clamps use a pump with the new VFD. The Jomar IntelliDrive 85S at the show boasted 42% lower energy consumption than a standard model 85S and required a 40% smaller oil tank.

The answer was a electric motor/pump combination driven by a variable frequency drive (VFD) allowing the customer general flow adjustment without excess flow and the heat generated going back to the reservoir thru a relief valve. High pressure filtration was included to protect and clean the fluid as the skid would be used for several systems. The cart was placed on casters with a drip pan to allow for ease of movement throughout their plant as needed.

Centrifugal pumps are generally sized to operate at or near the best efficiency point at maximum flow. The maximum flow requirements, however, frequently occur for a very short period during the operating cycle with the result that some method of flow control is required. The traditional method to flow control has used valves, which increase system pressure, inherently waste energy, and generally cause the centrifugal pump to operate at reduced efficiencies.

VFDs (Variable Frequency Drives) can achieve reduced flow by providing variable speed pump operation. This results in reduced system pressure and operation near the pump"s Best Efficiency Point. In addition, maintenance costs might be reduced. This article will discuss the energy savings potential of variable frequency drives followed by a brief description of the operation and relative benefits of VFDs.

Centrifugal pumps are used on many industrial and commercial applications. Many of these pumps are operated at fixed speeds, but could provide energy savings through variable speed operation. Reviewing the affinity laws for centrifugal pumps and a typical operating cycle for a centrifugal application will show this.

Figure 1 shows the physical laws of centrifugal pumping applications. The flow is directly proportional to speed; pressure is proportional to the square of the speed; and power is proportional to the cube of the speed. These relationships can also be expressed numerically as shown in Table 1. Theoretically, it would be possible to operate at 50% flow with only 13% of the power required at 100% flow. Since the power requirements decrease much faster than the reduction in flow, the potential exists for significant energy reduction at reduced flows.

These characteristics are important when one considers a typical duty cycle for a centrifugal pump application. A typical operating cycle might be represented by the bar chart shown in figure 2. Centrifugal pumps are generally sized to handle the peak flow requirements, which typically occur for very short periods of time. Consequently, the equipment would be operated at reduced flows most of the time. For this example, the system would be operated below 70% flow over 94% of the time. Thus, this sort of duty cycle could provide energy savings by variable speed operation of the centrifugal pump.

An understanding of the basic operating characteristics of centrifugal pumps is necessary to apply variable frequency drives to this particular application.

Figure 3 shows a centrifugal pump curve describing the head (or pressure) versus flow characteristics of a typical centrifugal pump. This curve shows that the centrifugal pump will produce limited flow if applied to a piping system in which a large pressure differential is required across the pump to lift the liquid and overcome resistance to flow (as at point A). Higher flow rates can be achieved as the required pressure differential is reduced (as at point B).

To determine where along this curve the centrifugal pump will operate in a given application requires the additional information provided by the system curve. This curve, shown in figure 4, represents the characteristics of the piping system to which the centrifugal pump is applied. The head required at zero flow is called the static head or lift.

This shows how many feet of elevation that the centrifugal pump must lift the fluid regardless of the flow rate. Another way to describe static head is to think of it as the amount of work needed to overcome the effects of gravity.

The intersection of the centrifugal pump and system curves shows the natural operating point for the system without flow control, as shown in figure 5. This intersection would generally be chosen to ensure that the centrifugal pump is operated at or near its best efficiency point.

Figure 6 shows a typical centrifugal pump and efficiency curve for operation at a fixed speed. It can be seen that for fixed speed operation, the efficiency varies as flow is adjusted. For variable speed operation however, the affinity laws predict that the centrifugal pump curve will shift downwards for reduced speed and the efficiency curve will shift to the left in such a way that efficiency will remain constant relative to points on the pump curve for reduced flows.

Historically, fixed speed AC motors have driven centrifugal pumps and reduced flow has been achieved by using control valves as shown in figure 7. Closing the valve reduces the flow by increasing the friction in the system. The modified system curve and the new operating point can be represented as shown in figure 8. Note that the desired reduction in flow has been achieved, but at the expense of increased system pressure relative to 100% flow.

Reducing the centrifugal pump speed causes the pump curve to shift downwards as shown in figure 9. Since the operating point is still determined by the intersection of the reduced speed pump curve and the system curve, it is possible to achieve the same reduced flow as achieved with a valve, but at significantly less pressure.

In addition to energy savings by VFD, which are discussed in detail later, operation at reduced pressures can result in longer pump seal life, reduced impeller wear, and less system vibration and noise. These benefits could provide additional savings over potential energy savings by variable frequency drive.

Therefore, for any given liquid, the power that the centrifugal pump must transmit is proportional to the head times the flow and can be represented by rectangles for each operating point as shown in figure 10.

The valve control rectangle includes both the dark and light shaded areas. Speed control uses only the lighter shaded portion of horsepower. Therefore, the potential energy saving available at this particular flow point is represented by the darker rectangle. This situation results in a substantial reduction in output power required through the use of variable frequency drive control rather than valve control (see differences between VFD and valve control). Relating this reduction in required output power to input power, which is the basis for the user"s power bill, requires consideration of the efficiency of the centrifugal pump and flow control elements.

(2) Slip control refers to fluid and magnetic couplings, often referred to as hydraulic or eddy current couplings. Wound rotor motors are also slip devices.

Thus, the first step toward realizing energy savings on centrifugal pumping applications is the decision to use VFD for pumps. The second step is to use the most efficient VFD that meets the application requirements.

VFD energy losses can vary substantially between VFD types, Solid-state drives have much lower losses than slip devices and closely approximate ideal, 100% efficient operating characteristics as shown in figure 11.

Centrifugal pump efficiencies at various operating points are readily available from the pump manufacturer in the form of an efficiency map superimposed over the centrifugal pump curves for various impeller sizes as shown in figure 12.

The state-of-the-art has progressed dramatically in electronics in recent years. Advances in logic have produced large scale integrated and microprocessor devices that will continue to increase the capability of VFDs. Improvements in thyristors have resulted in decreased size while the development of IGBTs have expanded capabilities and size ranges. VFDs are expected to continue decreasing in cost and increasing in performance in the years to come. Besides longer-term energy savings, the initial cost differential between installing a VFD / motor package as compared to an AC starter/motor package is continually diminishing.

Dramatic increases in energy costs in recent years have made variable speed flow control through the use of VFDs economical in many instances. Large users of centrifugal pumping equipment would be wise to begin gaining experience with these VFDs now.

The most important choice to be made in choosing the VFDs is the decision to select a non-slip, solid-state VFD. Any such VFD can offer dramatic energy savings by efficiently matching the energy consumed to the hydraulic load requirements at any given moment.

In general, if the electrical engineer does not fully understand the operation variables of the pumping operation, he will not be able to design a proper operation and protection gear.I highly ...

Mechanical VFDs include the following subtypes:Variable pitch drive – a belt and pulley drive where the pitch diameter of one or both pulleys is adjustable, giving a multi ratio and hence a ...

There are two ways in tension control, one way is to control the output torque of the motor, the other way is to control the motor speed. Variable frequency drive (VFD) open-loop control mode is ...

Hydraulic pumps are NOT the same as water pumps! they are Positive Displacement pumps, not centrifugal. They do indeed need high starting torque and in fact a centrifugal pump is exactly the opposite. DO NOT use the "Pump Control" macros in a VFD for a hydraulic pump, it will not work. But it can be done, just be sure to use a "vector" drive so that you can get full motor torque at start-up and use the "Constant Torque" output pattern.

But why are you thinking of putting a VFD on a Hydraulic pump anyway? Lowering the speed may not give you the performance you are thinking of. Don"t get me wrong, it"s done all the time because running the pump slower when you don"t need full flow does save a little energy compared to full speed and a recirc. / throttling valve, and it is also a lot quieter. But at really slow speeds you can run into HP problems and have to have the valve control there anyway. So if you are going to spend a lot of time running at very low flow rates, you might want to rethink the cost of adding the VFD.

EXCEL PUMPS PRIVATE LIMITED has 3 decades of on hand experience in the field of manufacturing & marketing of various types of Industrial Pumps and Pumping Systems.

During our journey, we invented optimum & economic pumping solution for various installations. Honoring the commitments of Pump Performance is our Prime Face for consistent relationship with our customers.

There are some applications where a pump must discharge into a closed system to meet continuously varying demands where a variable speed pump could pay for itself in a short time. But what about water and wastewater systems?

(First, a digression. There is no such thing as a variable speed pump. A pump is a pump. What constitutes variable-speed pumping is a variable-speed motor attached to a pump. A variable frequency drive (VFD) is the best technology these days to produce variable speed. So, I’ll call the pump, VFD and motor together as a variable speed pump.)

The selection of the pumping technology should be based on life cycle costs (plus some other considerations) and depends heavily on the nature of the pumped system. There are essentially two types of systems – those that have floating storage and those that don’t. This makes a big difference in the type of analysis required.

Systems with storage have a significant advantage in pumping in that it is possible to turn the pumps(s) OFF. This storage can refer to an elevated water storage tank or a sewage wet well. If you correctly select the right constant speed pump, you can run it at an efficient operating point to fill the storage tank or drain the wet well and turn it off. I’ve done a lot of calculations along these lines, and constant speed pumping almost always wins.

But as with everything else in life, there are exceptions to the rules. The first exception depends on the shape of the system head curve. Most water, and to a lesser extent, sewage pumping involves a fairly flat system head curve. Water is lifted from one pressure zone to the next higher one or lifted over a drainage divide. It is very difficult to turn down the speed without seriously hurting the efficiency. However, if you are pumping across flat ground, most of the energy is used to overcome friction, and the flow can be adjusted without having as much detrimental effect on efficiency. The friction-dominated case may favor a variable speed pump.

In systems without storage, it’s not possible to turn pumps off, so the pump station must meet the instantaneous demand. This means that during low demands, a constant speed pump would need to run far to the left on its curve and the pump would be pumping at a high head and low efficiency. A variable speed pump would be the clear winner—but not always.

The pump station must meet peak demand with the largest unit out of service. The typical configuration for a small to medium pump station is usually two pumps, with each sized to meet peak demands. But, in most situations, the peak demand rarely occurs, and the one running pump is running at low efficiency, especially during low flow periods.

Is there a better configuration than these two pump solutions? Enrico Creaco and I (Walski and Creaco, 2016) tested a wide range of configurations (see below) over a wide range of flow in a paper we wrote using WaterGEMS to calculate life-cycle energy costs.

As expected, the configuration with two constant speed pumps had the worst life-cycle cost. But surprisingly, the second-worst was the two variable pump setup that pretty much everyone uses. Configurations with three pumps (or for very small systems, two pumps, and a hydropneumatics tank) proved to be better than two variable speed pumps. All the three pump configurations were fairly close to one another in cost. The reason they were so good was that their best efficiency point could be matched fairly well with the most common demands with only one pump running. For those cases, where demands were high, simply turn on the second pump until the demand drops.

A lot depends on the actual flow distribution that the pump station will encounter. If the peak flow is 800 gpm and the average flow is 750 gpm, then any configuration will work well. However, if the peak flow is 800 gpm and the average flow is 200 gpm, then it will be virtually impossible to make the two-pump designers work efficiently.

In an earlier blog (Abusing Affinity, 4 March 2021), I mentioned how the calculations of head and efficiency for variable speed pumps are governed by the pump affinity laws, and sometimes those folks selling VFDs misrepresent the affinity laws to make their product look more beneficial than it really is.

Another issue is the fact that the VFDs themselves introduce a certain amount of inefficiency. They work by breaking up the smooth sine wave of alternating current into pieces and reassembling those pieces in a sine wave with a lower frequency, thus varying the pump speed. The problem is that this reformulated output wave is less than 100% efficient. This loss of efficiency is sometimes called the “parasitic energy demand of the VFD”. VFD salespeople don’t like to talk about this, and if you ask them for data about VFD efficiency, they will only provide data at 100% of full speed, which is not the case you’re looking for, or respond along the lines of.” Hey, do you think the Chiefs will win the Super Bowl next year?”

How do you decide on the best configuration for your pump station? I’ve been trying for years to come up with some rules-of-thumb to decide on the best configuration, and the best I could come up with are the paragraphs above.

What you need to do as a conscientious engineer is try many designs to arrive at the best pump selection. The most tedious step in a good evaluation is calculating the life-cycle energy cost because the pumps must work over a range of conditions. In my early days, I did these calculations manually, and you needed to make a lot of simplifications to make the effort feasible. Later, I graduated to spreadsheet calculations, but that still didn’t capture all the hydraulic and cost variability. Now, if you start with a well-calibrated model, WaterGEMS and WaterCAD can give you the results you need with a few mouse clicks.

Walski, T. and Creaco, E., 2016, “Selection of Pumping Configuration for Closed Water Distribution Systems”,Journal of Water Resources Planning and Management,142(6), DOI: 10.1061/(ASCE)WR.1943-5452.0000635.

But the problem of reducing the pump speed is that now you have reduce the available volume and pressure, the problem with this is, if the door requires X amount of force to close what is there to tell the VFD to speed up the pump to apply enough pressure to get the job done?

Seems to me that in this application there would need to be some PID"s to tell the VFD where the door is at, and what speed it is closing at, and when it has reached the latching/open stop, of course the amperage of the pump motor and pressure transducers and flow rate sensors could be used?

And in all of this, as was pointed out, rating of the pump motor, cooling, and how far the distance conductor run between the pump motor and VFD"s will all have an impact of the longevity of the motors.

Jraef has helped me out in many of the understanding of VFD"s and their limits, as this is kind of a new field for me, and one I will be going to school for with my new job, but I do love the design work something like this presents.

Siemens’ Sinamics servopump is built on standard components such as the Sinamics S120 drive platform and distributed I/O, and offers users increased machine output and reduced energy costs by up to 50%.

With any fluid power system, efficiency is always top of the mind, so components and advanced technology that can improve energy consumption are increasingly necessary. To that end, the NFPA last year commissioned a survey to examine the current and potential use of variable speed drives (VSDs) with hydraulic pumps.

Not surprisingly, the overall results showed that respondents believe that the use of VSDs in hydraulic applications will increase over the next three years. They cited VSDs’ high-energy efficiency, improved reliability and low operating cost as key determining factors in the increase of their use. On the opposite end of the spectrum, when asked what discourages the use of VSDs, respondents pointed toward high acquisition or upfront costs, lack of maintenance and after-sales support for VSD technology, and lack of design expertise in their use.

The four main manufacturers of variable speed drives in the U.S. include Eaton, Parker Hannifin, Siemens and Bosch Rexroth. Here, we spoke with representatives from three of those companies—Lyle Meyer, global product manager, Industrial Drives, Eaton Hydraulics; Lou Lambruschi, marketing services and e-business manager, Parker’s Electromechanical and Drives Div.; and Craig Nelson, marketing manager, Drives, Siemens Industry U.S.—to learn how VSDs can change the way hydraulics function in an industrial setting.

Meyer: There are three advantages variable speed drives offer the market— low noise, longer life and higher efficiency. Depending on what a particular customer’s needs are, low-impact noise could be a primary reason to incorporate a VSD into a machine. Eaton’s pumps are capable of running down to zero rotations per minute, so reduced noise in the overall system—and better overall sound quality—are significant features.

Efficiency is a key driver that brought about Eaton’s variable speed drives solution, and there are several market influencers that have led to innovative hydraulic pump and system level technologies—government regulations and energy costs. Energy costs continue to increase over time, and government regulations are continuing to require fewer emissions, both of which have led machine builders to consider more efficient electric motor solutions. If hydraulic pumps cannot operate in the speed ranges needed to complement the wider speed ranges of VSD motors, they can be replaced by electro-mechanical options.

There’s another part about it, too, which is environmental … as well as being “green” on the cost is the environmental impact of being less likely to have hydraulic leaks around your plant. That’s something that everybody really has to keep a big check on because of its environmental impact.

Lambruschi: The biggest advantage tends to be energy savings. Other types of pumps will see increased controllability, quieter operation and potentially longer life. Drives equipped with fieldbus communications allow for local or remote monitoring of the pumping process, allowing access to parameters like pump loading, running time and energy consumption.

There is such an installed base of hydraulics out there. I think most of the new machine users are not even giving it a second thought of going with the new technology. What’s been slower is driving people to retrofit out their existing working system for something that’s better, more efficient, takes up less room, less oil, less noise, and all the other advantages that it provides.

Meyer: Generally, there are three things that are holding people back from adopting VSD technology—perception, cost and system design. Perception is now the main issue preventing customers from adopting VSD technology, whereas the number one issue in the past was overall cost. Machine builders initially thought a VSD solution for a hydraulic system was extremely expensive. Today, it is equally cost-effective to make a system hydraulic variable speed as it is to make it electric. Hydraulic components don’t change, and electrical components have experienced much lower costs in the past five years. Fixed-speed starters used to be the lower cost, but now variable speed drives are generally the same or lower cost as fixed speed.

Lambruschi: In many retrofit applications with known operating cycles, an estimated payback period can be calculated. In actual applications, this has been shown to be less than 12 months. Cost concerns can also be offset by the fact that many power utilities offer rebates or incentives for the purchase of variable speed drives for pumping applications. Also notable is the fact that cost savings are not just achieved by efficiency, but by less obvious factors such as reduced maintenance costs and enhanced pump life.

Meyer: Duty cycle is key to balancing cost with efficiency. Pumps are capable of multiple speeds, including zero speeds that allow operators to incorporate VFDs—the building block for smart machine architecture. Before you can start designing machine control, you need components that can handle that level of control. If there are cost increases with a VSD, then they must be paid back on the duty cycle.

Lambruschi: Within pumping applications, we see particularly good growth in the use of drives on hydraulic power units, replacing proportional valves and similar technologies with a more efficient approach. Growth is seen in multiple regions globally, with concentrations in areas where new production facilities are being built or older ones modernized.

Nelson: For us, it’s all about ease of use. We offer this solution with our standard sizes and software. We use the same components that we use for most of our typical servo systems, not just our servopumps, like our Sinamics S120 drives, 1FK7 motors and 1PH8 motors.

Lambruschi: Pre-programmed pump application macros and pump-specific parameters, as well as environmental features like conformal coated PC boards, make Parker drives more user-friendly and suited to the tough environments that pumping applications are often a part of. Larger drives used on higher power pumps are constructed with field replaceable power modules, allowing for quick and easy maintenance and minimal downtime in the event of failure. Parker is also uniquely positioned to be a complete system provider, being a manufacturer of pumps, hydraulics, and fluid handling components in addition to variable speed drives.

Meyer: Eaton’s biggest differentiator is low speed—our pump products have been tested down to zero speed. Eaton’s pump products are capable of operating at speeds that are as low as or lower than competitive offerings.

In the past, Eaton pumps or competitive offerings could simply be turned off; however, that function added some complexity to the circuitry. A pump capable of running at zero rpm takes a lot of complexity out of the circuit, in terms of holding pressure. Eaton’s zero-speed capability decreases system complexity and further enables the machine designer to flexibly design the system.

VFD technology was developed in response to the limitations of AC power. AC motors, such as the ones powering industrial pumps, rotate at a rate set by the incoming power and the number of poles inside the motor. Since AC power in the US is supplied at a standard 60 Hz frequency, this means that standard single phase two-pole motors spin 60 times per second.

Adding more sets of poles reduces the speed without any need to alter the incoming electrical frequency. However, you can’t just swap out an electric motor with more or fewer poles every time you need to change the operating speed of a pump. Transistor systems that allow you to turn specific motor poles on and off have been available for decades, but these systems are complex and often lack the fine control needed for industrial pumping. Instead, VFD’s change the frequency of the power supply, allowing for exact and immediate adjustments to the pump operation.

The VFD works by taking in AC power at the 60 Hz frequency, converts it into direct current (DC) power through a rectifier circuit, and sends it through a DC bus to filter the voltage further. Then, power reaches the inverter which creates pulses of DC energy that function like AC current. The pulsing nature of the output mimics AC power enough to create the correct induction processes needed to spin the rotor of the motor. Since DC is easier to control in voltage and frequency, using it instead of true AC power allows the VFD to adjust the electrical supply on the fly. A series of transistors, especially the Insulated Gate, Bipolar Transistor (IGBT), give manual or automatic control over the power output and the resulting EDDY pump performance. Power is easily increased to a sludge pump under heavy load and then dropped again after a blockage passes or the texture of the slurry or sludge being pumped changes.

By using variable speed drive technology, instant savings can be realized. By automatically adapting the pump’s speed to match changes in demand, variable speed drives are the perfect addition to many hydraulic systems.

An example of energy saving tests run by Parker on a hydraulic press system clearly show that substantial savings on energy are possible using a variable speed drive to reduce motor speed during parts of the machine cycle with low flow demand. Plus, by over-speeding a pump at times of low pressure demand, a second pump could be eliminated.

The results in this case  were highly desirable in any manufacturing environment:An average power need of just 34 HP (25kW) compared to 50 HP (38kW) using an unregulated pump, over the entire press cycle

Few competing companies can claim the expertise in both hydraulics and electronic drives that Parker brings to the table. With many sizes and styles of pumps and HPUs, and VFDs ranging from fractional to 2000 HP, few applications are out of Parker’s range. To save time and expense, multiple pre-configured VFD programs are available, covering applications like P (system pressure) control, Q (pump flow) control, and Hi/Lo control.

In engineered pumping systems, success most often begins with the quality of the specifications and drawings. A pumping system specification that is pulled together in a piecemeal, component-by-component way without a complete understanding of the application, concerns, potential pitfalls and ongoing maintenance requirements, can be a roadmap to failure. Conversely, a specification that considers performance needs, which includes installation, project coordination, and lifecycle cost, driven by the experts who understand the entire process and each pump application within it, is likely to exceed customer expectations.

This white paper provides a guide to facilitate coordination of the Variable Frequency Drive (VFD) with the pump and the motor (driver) within pumping system(s) contract documents (specifications and drawings) for a successful, fully functional pumping system.

12/24 Volt DC hydraulic pump motors for sale, price cheap, 500W, 800W, 1.6 kW, 2.2 kW and 2.5 kW hydraulic pump motor for selection, hydraulic pump motor is widely used in dump trucks, fixed boarding bridges, lifting platforms, van wings, car lifts, vehicle headboards, etc. It has the characteristics of high speed and small rotational inertia, which is convenient for starting, braking, speed regulation and commutation.

Hydraulic motor and hydraulic pump, all with the help of sealing work in the capacity of the transformation to complete the kinetic energy, - the same with the flow distribution organization. Hydraulic motor in the keyed high-pressure liquid state effect, into the liquid cavity from the small increase, and the rotating components caused by the torque, in order to get rid of the load resistance torque, to complete the rotation; In addition, the motor back to the liquid cavity from the large shrinkage, to the car tank or pump suction pipe mouth back to the liquid, the work pressure is reduced. The pressure wave state continues to enter from the leakage port of the hydraulic motor, and discharge from the return port, then the motor rotor of the hydraulic motor rotates continuously and opens to the external work.

From the theory. In theory, in addition to the valve type hydraulic pump, other ways of hydraulic pump and hydraulic motor with cross, can be used. In fact, because the performance indicators and provisions are not the same, the same way the pump and motor in the structure is still different.

The hydraulic motor is keyed into the liquid containing the working pressure to promote its rotation, so it is necessary to ensure the original confinement, without having the ability of self-priming. While the hydraulic pump - generally must have self-priming ability.

Hydraulic motor should be able to forward and reverse, so the internal structure of the hydraulic transmission must be symmetrical. Hydraulic pump is generally all single-sided rotation, in the structure of the general do not have this limit.

Hydraulic motor speed than a large range, especially when the speed is relatively low, super piston hydraulic motor should be able to ensure that all the normal work, so should be selected with roller bearings or negative pressure rolling bearings, if the choice of gas pressure rolling bearings, it is not easy to produce grease film. And the hydraulic pump speed is relatively high, the general shift is small, there is no such provision.