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- เผยแพร่เมื่อ 28 มิ.ย. 2024
- I cover VFD theory and how we use an inverter for pulse width modulation to control electric motor speed. This is ment for hvac technician and building engineers as hvac training videos.
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I thank you for this very informative vfd training video. Appreciate your time you put into this to help others out.
The dry/erase board is great for explaining, but to help some technicians an actual vfd to show the parts of the system is key.
Great presentation. Accurate information and good flow. Covered most of the information I received in the drives class provided by our union school.
I’m kinda old school, really enjoy a live class, and I think it was really good information. I’m an Ohio tech of 30 years and I believe that there is nothing better than in class experience between the class and the materials being talked about. I have learned so much from a chalk board
Whiteboard is my preference over PowerPoint
New to your channel. Thank you so much for the detailed info you’re providing in these videos. I will share this with my coworkers. I’m 7 years in the supermarket field and still always trying to improve and become more knowledgeable.
This is a great video. Thank you for your time and effort going into this. Much obliged.
Great video loved the troubleshooting portion just bought a new Meggar that I need to utilize more
Sir, you may also include the BMS automation system such as control points set up..thank yoy
Sir, thank so much, very nice explanation.
Sir, just want to request you one thing. Most of the technicians in are not much educated. practically they are very good so you should explain to the in different way which will be useful to them also. I mean practical methods. Thank you sir.
Great content
Good job, thanks
Good information thank you keep posting videos like this it gives knowledge to the new guys like me knowledge is power!!!.Just a friendly tip get some new markers or brighter ones kind of hard to see
VFD - Variable Frequency Drive...Basically takes Ac voltage and manipulates it into DC voltage where it is then controllable as far as the Hertz is concerned so they can speed up and slow down large HP motors. Actually ECM motors in Residential units use the same principal.
Use ec motors on commercial condensers too. The ones I run into run off potentiometer pressure controllers, powered off 24 vac transformers, get their high pressure readings off transducers, then that controller sends a 1 to 10 Vdc signal to the controller in the motor. Just FYI in case anybody runs into those, I had to learn on the fly but there's several different setups.
ANOTHER SOLID MOMENT IN HISTORY...
Hi can you pls make video in programming daikin vrf central monitor
Thanks for good topic,, is there a certain order for this lessons?
@37:31 it is impossible to have a power factor greater than 1. Please see en.m.wikipedia.org/wiki/Power_factor
Would you have to have a Oscilloscope Multimeter to measure voltage on a vfd
Canada 60 hz 600 volts
First time installed one and omg you have to make sure that it is right to the T if not it won’t do anything.
They are extremely particular, especially when you start programming PID's
@@HVACTIME that is true man! Keep up the great work you do this field is unpredictable at times.
I can't seem any diagram it just looks white board .
I can't see you drawing😢
Ya, ive gotten a darker set of marks now for that reason.
I believe you have the VFD theory incorrect. What you are explaining is a PWM drive for a universal or DC motor.
First, the input AC, whether single or 3 phase, is rectified by a full wave bridge, and then filtered by a bank of capacitors. This creates the DC operating bus for the VFD.a
A VFD output will still be a sinewave, of varying frequency and voltage. The voltage will be lower at lower frequency so as not to saturate the windings at lower frequency and is controlled by the processor and sensing in the VFD.
The inverter creates a carrier of about 10 to 16 khz and that is what you hear at lower speeds. The drive synthesis a sine wave, made up of the chopped DC bus.
The speed control comes from the inverter creating a variable frequency sine wave by using the carrier (which is fixed frequency), and controlling the amplitude that the carrier changes at, hence the variable frequency.
Because the motor is going to try and follow the magnetic field(s) created in the stator, varying the frequency will vary the speed of the rotor.
There is no PWM in an AC VFD drive, just a fixed carrier and a varying frequency that the inverter creates.
This is an extremely simple explanation, but I wanted to correct your explanation on a VFD operation.
That sounds nice but all the documents and training ive been through on drives supports my explanation of whats physically happening in the drive. End of the day the inverter still has gates that creates the pulsing. Its not a true AC sign wave.
@@HVACTIME you’re right, it’s a PWM approximation of a sine wave. Your meter reads it as a sine wave because it’s good enough, but if you were to measure the voltage peaks, even when the drive is making a 100V sine wave the peaks are still at full DC bus voltage.
@@Ak3rn0and @HVAC TIME, I have to disgree and agree with @Pomonabill220!
Think about it- 460 Vac [Vmax] does not equates [rms] to 600 Vdc [heat] or 600 effective voltage.
In retrospect, the Vmax applied to a capacitor reacts causing what is call capacitive reactance, meaning power [watts] is losted and current [electrical intensity] is increased, which needs to be inverted to control frequency [Hz].
Reason being, motor is an inductor therefore an inductance reactance of the motor occurs that also causes a power [watts] loss as electrical intensity [current] decreases creating phase shift.
To elaborate further, an inverter job is to convert DC to AC voltage and a rectifier job is to convert AC at full wave bridge to DC voltage in an AC VFD configuration.
Therefore, there is no PWM [Pulse Width Modulation] in a inverter driven AC VFD [Variable frequency Drive].
However, in a DC configuration, PWM [Pulse Width Modulation] drives are typically low voltage driving DC motors- An example is the use of EEV soleniod or EEV stepper motor whose voltage is rectified from AC to DC at half wave, a voltage pulsation resulting in the term PWM.
@@HVACTIME , I came to an understanding what you are talking about; Older drives uses the method of current inverter, and variable voltage controller with the use of SCR [Silicon Control Rectifier] or Thyristors, as discussed, which is still in circulation, may I add.
What you are discussing, however, is the latest emerging drive technology for the HVAC trade using AC PWM [Alternating Current Pulse Width Modulation] that is bridge at (Full Wave), not half, and controlled with (IGBT Power Transistor).
Great information Bud, keep in mind though (full wave bridge, not half wave) for AC PWM VFD [Alternating Current Pulse Width Modulation Variable Frequency Drive].
Overall, great information!
@@HVACTIMEThe SCR bridge is converting the complete 3∅ sign wave to DC, with 6 SCR's. 3 SCR's take the positive half cycle and the other 3 take the negative half cycle. DC created from 3∅ is much easier to filter because you never cross through 0V. Just need to smooth the ripple, but it never goes to 0V. If this were 1∅ the capacitor bank would need to be much larger.
The PWM signal is AC as far as the motor is concerned even though, looking at it in a oscilloscope it is a bunch of 600v DC pulses going positive and negative. The field in an inductor has a delayed reaction similar to a capacitor, so the field in the motor doesn't instantly collapse when the signal disappears form the VFD. Remember that a motor is nothing more than a spinning transformer.
der labert ein bisschen viel scheiße
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