Wednesday, May 3, 2017

HVAC Training | VFD Basics

Variable Frequency Drive Essential

(VFD Course introduction video)

This VFD drive training video is a preview of the VDF basics, from the essentials online course at

Variable Frequency
Drive Essential, is a VFD training online certificate course
where you learn how VFD motor control works and other essentials. The online course is designed to familiarize students from beginner or expert with the essential VFD types, features, functions and benefits of them. Be it a VFD pump, motor inverter or other AC motor speed control.

VFD Basics Video

Welcome to Business Industrial Network (
This training this module will cover variable frequency drive essentials. It is designed to provide product knowledge for all levels. At the conclusion of this module you can register to receive your certificate of completion. Be sure to take advantage of obtaining this documentation serve as proof that you completed the online course.

Now let's get started! PID control is a very popular application for industrial processes the letters stand for Proportional Integral and Derivative. The three calculations that comprise that is sometimes called a Loop. It incorporates an algorithm or formula. It makes calculations of the process and provides feedback to the controller that allows the desired output. An entire session could be developed to cover this topic in detail. A simple explanation however might be to examine a cruise control system on an automobile. A driver sets a desired speed and the controller takes into account varying conditions such as wind conditions and inclines. As the controller senses the varying conditions calculations are being made to ensure the desired speed is maintained.

Here is the block diagram representing the process. Note that each element has its own formula. It looks complicated but the operator merely needs input a few values and the controller then takes over the process. We'll examine this concept in more detail later in this module. No doubt the single biggest market for VFDs are into the HVAC industry. You will hear this acronym a lot when discussing drives. It stands for heating ventilation and air conditioning. Many reports site that 15% of the world's energy consumption is from motors used in HVAC application! That's right ceilings of every commercial and industrial building are a multitude of motors that provide heating and ventilation for areas inside the building. These are fans, air-conditioning units and exhaust systems. During low occupancy can adjust the speed motors are running thereby saving money on electric consumption by as much as 3 see how this is accomplished a little later on in our discussion.

Variable frequency drives are set up by using the keypad on the drive. This key pad is also used to run drive. Some drives automatically going to the run mode. It can be easily changed to the monitor mode by toggling the membrane mode switch again pressing the mode switch. It is important to note in programming manufacturers. In this instance, the Schneider Altivar 212 uses the "symbol ""tHr"" for inputting the thermal" overload value. Most drives can be set up very easily for routine applications by inputting information from the motor nameplate. Namely motor current nominal voltage and desired overload current level the same as the full load current of motor. Many manufacturers offer an alternative LCD keypad with English text that spells out the function rather than provide a symbol. In those cases, interchanged with a standard supplied keypad or as a remote mounted kit. Coming up we'll talk about the other VFD functions available from most drive manufacturers.

In the definition VFDs varied the speed of an AC motor. Well then at full speed the desired speed? This practice would be equivalent to driving a car with the accelerator pressed to the floor applying a brake with your left foot to meet the desired speed limit. And that sounds a little bit far-fetched. But variable frequency drive allows for energy efficiency by only utilizing the exact amount of power operate at a speed that load requires. In addition, the amount of mechanical stress the equipment are minimized. Lastly some applications as we will see such as conveyors smooth operation and changes in speeds offered by a VFD. A typical sewage treatment plant utilizing these equipment applications. This equipment will run an optimized electric power while eliminating mechanical stress and saving money on cost and maintenance. A popular application for pumps and compressors is a duplex design. In pump applications and alternator is used with either a pressure transducer or a float switch. In these applications starts when the pressure is required. As the initial pump comes up to full speed more pressure is required pump starts. Once the system is satisfied ...

Drive manufacturers have the ability to accept feedback signals PID loop refers to the cycle of control. Open loop feedback going directly to the drive. A closed loop system however accurate control of the drive. In closed-loop applications and a speed reference are programed. If the actual
speed varies from the setpoint, referred to as an "off the set point", offset for short. Let's recap that happened ...

The marketplace is jam-packed with manufacturers variable frequency drives. This slide will feature some of them. Eaton electrical has wide variety of drives from different applications. One popular segment of the line is their SVX 9 general purpose and SPX 9 high-performance models. Much of this offering are Bakken drives re-branded for Eaton. Franklin electric out of Portland Oregon's their p- series type for high performance. And PowerFlex 755 for the harmonic mitigating drives. Siemens labels their drives Micro Master SiMatic and SiMotion. They cover a wide variety of applications including HVAC. Some manufacturers will offer low end VFDs as part of their line. These are labeled as micro and mini. they are also sold in board level designs. Micro is the smallest features. Mini offering a few more features such as a display readout. Popular among OEM's are board level versions of these drives. OEM's mounted in their equipment...

Let's take some time to go over the standards that apply the variable frequency drives. NEMA Electrical Manufacturers Association a standard title NEMA ICS 618 This applies the general purpose adjustable frequency drives that include power conversion AC motor or motors. This also applies to systems connected to live voltages of the 1 kV AC 5 frequency up to 6 Commission has issued electromagnetic capability adjustable speed electrical power drive systems part 3 requirements and specific test methods. The CE mark has become ...

Now why do engineer is specified bypass on drives?  he primary reason is to keep machines critical nature from the 197 early stages of development. There are many failures with the circuit boards and SCRs. Customers were anxious to obtain energy savings but the high failure rates caused  manufacturers to offer bypass packages as a backup. Bypass was considered    low-cost method to keep the motor running in case of a VFD going down. Today's VFD failure rates are much lower than bypass contactors. Therefore, the costs appropriated for bypass components in some cases channeling toward a spare drive. This is especially important is a backup for several drives inside a plant. Redundant VFDs critical applications. As seen here they work on the principle that if one VFD fails maintained by a second VFD automatically takes over. Redundant VFDs have been around for years only recently has this concept become cost effective. As the VFD...

Variable frequency drives their compact size into existing motor control centers. Replacing the standard starter or multi speed starter This represents a considerable energy savings opportunity for customers. However, caution needs to be exercised since the VFDs generate considerable more heat than a conventional motor starter. Proper ventilation needs to be addressed. Also...

Let's go through the selection factors that apply the variable frequency drives. You need to know the horsepower voltage and if the voltage is single-phase or three- phase. Next you need to know whether it's constant torque or variable torque. Next you will need to now of a disconnect is required disconnect is required breaker for a switch and the current rating or fuse clip rating that applies. Next you need to find out if an output contactor is required. If an input line reactor is required or a load reactor. If dynamic braking is required. And then bypass is required or three contactors required. What are the pilot lights and switches required the bypass operation? Is redundancy required to now the NEMA or IP rating of the enclosure. And lastly if any special boards are needed interfacing with network system or with an encoder.

To take the full Online VFD Essentials Certificate
Course, see

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