A variable frequency drive (VFD) transforms the input mains of constant voltage and frequency into a voltage and frequency range that can be varied to control motor torque. That will give you the actual energy that you pay for. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse! Since frequency-drives often are physical protected in small cabinets or small rooms, ventilation - or even cooling - may be needed to avoid overheating. Register for the world’s largest manufacturing technology forum for free today to stay in the know. Variable frequency drives are common for controlling the electric motor speed in applications with fans, pumps, compressors, elevators, extruders etc. i.e Efficiency of the pump is the ratio water horse power to break horse power. browsing data or IP addresses) and use cookies or other identifiers, which are necessary for its functioning and required to achieve the purposes illustrated in the cookie policy. Google use cookies for serving our ads and handling visitor statistics. "what the grid will see is the power draw from the VFD only, not the motor itself, correct?". . Most VFDs on the market now will provide you with the kW output and if you look at their technical data, they should give a part-load efficiency percentage of the VFD itself. In case of sale of your personal information, you may opt out by sending us an email via our Contact Us page. The VFD acts as a "buck regulator", and in those voltage conditions, output current may be larger than input current. If essentially a constant inlet gas density (this fan is inside a building), then the motor bhp will follow standard fan law, whereby BHP2=BHP1x(RPM2/RPM1)^3. Copyright © 2020 vBulletin Solutions, Inc. All rights reserved. So even the lousy power factor is on a lower current. We'll bring you the most relevant peer-to-peer conversations happening in the trade and tips and tricks to help you get the job done. A PWM VFD uses a series of voltage pulses of different lengths to simulate a sinusoidal wave Fig. Those numbers are pretty close. the hope is that we can demonstrate enough savings to justify the cost of the drive in short order. "Jimmy Carter, "If I had eight hours to chop down a tree, I'd spend six sharpening my axe." Over 240 feet of piping involved in the system and I have an engineer on staff with a PhD in non-Newtonian fluid dynamics who will work those numbers. We initially went through the numbers with the customers and we were both rather skeptical but after the installs reality proved that the initial calculations for cost savings were very accurate. P t = power in to the frequency drive (kW) η d = variable-frequency drive efficiency. This white paper shows how collaborative robots can play a role in helping companies succeed in the Covid-19 world: to help with social distancing, ramp up new lines quickly and reshore existing products due to interrupted supply chains. When I look at, let's say an iPad AC adapter, the input/output rating on the charger states: Input: 100-240V 0.45A (AC) Output: 5.1V 2.1A (DC) I know that the input and output ratings are maximum. To calculate maximum heat loss - the maximum power transmission through the variable-frequency drive must be used. A fan taking atmospheric air can be -20F in winter, as well as 105F in summer, will have different motor draws (at a given fan speed) due to a change in gas density. Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. Maximum ambient temperature for a frequency-drive is approximately 40oC (104oF). However if you could find a vfd that will take an encoder input, in theory a proper "vector mode" control will drop the volts per hz as the torque on the motor shaft is decreased. PTC's Creo 7.0 has breakthrough innovations in the areas of generative design, real-time simulation, multibody design, additive manufacturing, and more! I'm not sure how the VFD affects this. Combined with (1), the mass flow (2) can be expressed as: mair = Pt (1 - ηd) / cp (tout - tin)         (2b). AddThis use cookies for handling links to social media. All Rights reserved. You should compare the power input with the power output on these devices: 1) The VFD input voltage, whether 1 or 3 phase is not allways the same as the output voltage. Practical Machinist is the easiest way to learn new techniques, get answers quickly and discuss common challenges with your peers. I am the Mechanical engineer who shifted to drive design for a living who will figure out the electrical savings . The mass flow of air needed for transporting heat from the variable-frequency drive can be expressed as, mair = Hloss / cp (tout - tin)         (2), Hloss = heat loss to the frequency-drive surroundings (W), cp = specific heat of air (kJ/kg oC) (1.005 kJ/kg oC standard air). To some extent this requires an encoder on the motor because the inverter can't (reliably) tell the difference between power leaving the motor through the shaft, and power leaving the motor windings (and magnetic core) in the form of heat. This website or its third-party tools process personal data (e.g. we were happy and the customers were very happy. Is there an efficiency or something for it that needs to be taken into account? Fan curves should tell you the require horsepower at the different speeds. Real-world case studies are provided. . It is the total power in to the drive that must be compared to the power output of the drive (minus the power lost in the drive operation). With more than 10.6 million unique visitors over the last year, Practical Machinist is the most visited site for metalworking professionals. Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! Promoting, selling, recruiting, coursework and thesis posting is forbidden. If at design point, the fan vendors states the motor will draw 10 bhp at 900 rpm, then at 300 rpm, BHP2=0.37 bhp. Our company has been doing a lot of retrofits on many of our filter systems that did not originally have VFDS on the pumps. I assume you’re asking about the RMS output voltage. To learn more, please refer to the cookie policy. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. Please let us know here why this post is inappropriate. it is not possible. Pump Input Power = P. Formula – 1. . The volume flow can be calculated by multiplying (2b) with the specific volume or inverted density: qair = (1 / ρair) Pt (1 - ηd) / cp (tout - tin)         (2c), ρair = density of air at the actual temperature (1.205 kg/m3 standard air). . 1 May ... think in terms of input vs. output. Q = Flow rate in m 3 /sec. Sign up for our eNewsletter now to stay in-the-know. Many these systems had total aggregate pump horsepower approaching 750hp. Fan curves should tell you the require horsepower at the different speeds. Energy/Time = Power. To calculate maximum heat loss - the maximum power transmission through the variable-frequency drive must be used. This is an actual example wherein the payback time for the VFD was three months and investment in the VFD returned more than four times its cost. Troubleshooting at the input starts with testing power and supply. Please read AddThis Privacy for more information. At frequencies below 60Hz, the output voltage from the VFD is below the line voltage. Thank you everyone for the excellent suggestions. However, since there is only L1 and L2 available the input current required to supply the rated maximum 3-phase output (7.1 Amps) will be higher than if 3-phase input power is available (approximately 1.732 time higher). Learn more about us. We don't save this data. Pump input power calculation formula or pump shaft power calculation formula. Then you have the motor and VFD losses to add in and that's your power required by the VFD. *Eng-Tips's functionality depends on members receiving e-mail. Rapidly explore innovative design options to reduce development time and expense, all within the Creo design environment. . An amount of the power transferred through a variable frequency drive to the motor is lost as heat. The density of air at 20oC is 1.205 kg/m3 and 1.127 kg/m3 at 40 oC. Since VI in = VI out (or Power in = Power out, P in = P out), the output current must be higher than the input current. I should have been a little clearer in my post though...this equipment is not actually running yet so I can't physically measure the power consumption. Already a member? Keeping our warfighters safe and delivering them a competitive advantage is a key goal of departments of defense around the world. How do I calculate the power consumption for this? Comparing current between input and output is not a correct comparison. Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. Click Here to join Eng-Tips and talk with other members! These applications will - due to browser restrictions - send data between your browser and our server. The heat loss from a drive can be expressed as, Hloss = heat loss to the variable-frequency drive surroundings (kW), Pt = electrical power through the variable-frequency drive (kW), The heat loss expressed in imperial units, Hloss = heat loss to the variable-frequency drive surroundings (btu/h), Pt = power in to the frequency drive (kW). Cookies are only used in the browser to improve user experience. It’s a goal shared by embedded computing manufacturers like Abaco: we never forget who we serve.This case study describes how a major international contractor integrated an Abaco single board computer at the heart of its CAS/CSAR solution. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. 1 on page 8). . Variable Frequency Drives - Generated Heat and Required Ventilation, en: variable frequency drive ventilation heat overheating work, es: variador de frecuencia de trabajo sobrecalentamiento de calor de ventilación, de: Frequenzumrichter Lüftungswärme Überhitzung Arbeit.

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