Categories

VFDs

Wiring a VFD to control single phase motor speeds

Friday, July 6, 2018

Variable Frequency Drive (VFD), generally it's using for controlling speeds of three phase induction motors. In technical it's possible to use a variable frequency drive for 1-phase motor speed controls, but we have to mention, control single phase motor speed by a variable frequency drive may cause overheat of the AC motor, as well as the service life. It's recommended to upgrade the motor to 3-phase AC motor, which you can also connect the 3-phase motor to single phase power supply by using ...

GoHz Variable Frequency Drive (VFD) Price List

Thursday, December 21, 2017

Variable Frequency Drive (VFD, also call variable speed drive, adjustable speed drive) converts AC to DC and then from the DC creates an output voltage at an adjustable frequency to run the induction motor at variable speed from 0 to 50Hz/60Hz. The voltage generally varies from 0 to rated input voltage as the speed goes from 0 to 50Hz/60Hz. VFD also can go above 60 Hz up to 400 Hz, but the torque falls off as the speed increases. The biggest advantage that a VFD has is the ability to save mon ...

How an induction motor works as a generator during braking?

Friday, November 3, 2017

Induction motors produce torque based on the DIFFERENCE between the rotor speed and synchronous speed. The applied line voltage produces a rotating magnetic field whose lines of flux are cut by the squirrel cage rotor windings. When those windings cut flux lines, a current is induced that produces a rotating magnetic field. Thus you have 2 magnetic fields attracting each other. If the induction motor is sped up by an overhauling load, the difference can fall to 0 and thus no current in the ro ...

Can I run a 3ph 120/208v 60Hz motor on 230/400v 50Hz?

Sunday, December 25, 2016

Depending on your local electrical code, if you need a grounded (earthed) system, you can use a 400V-Delta to 208/120V WYE transformer to feed a variable frequency drive (VFD), and then set it a 60Hz to supply 208V 60Hz to the motor. Although I do not normally recommend it, if it is appropriate for you to run the system ungrounded (unearthed), then you can feed the VFD with through a 400V-Delta to 230V-Delta transformer and then supply the motor with 230V 60Hz power from the VFD. (As with mos ...

Starting torque of slip ring motor and induction motor with VFD

Monday, December 19, 2016

The torque speed curves are completely different between an induction motor and slip ring motor. You need to understand the differences. If you have selected your slip ring motor to limit starting currents you can short out the slip rings and run your motor but the starting torque is reduced unless you use some features on the VFD to boost starting torque.

If you are using it as torque control on a crane then ...

What let a VFD feeder breaker trips when turn it off?

Friday, December 9, 2016

Variable frequency drives should be protected by fuses. Why? Because the VFD itself has all the protection you require for your motor so the only item you are protecting is the Rectifier and DC bus. Then you will find it is actually really impossible to protect it as when it has a fault it is generally catastrophic and all you wish to do is to remove the faulty VFD from the network to enable the rest to continue. This must be as fast as possible to limit the damage and MCBs don’t really ...

How can I connect PLC to VFD?

Saturday, November 12, 2016

There are a couple of thoughts on this. You could connect a PLC to a VFD using a communication protocol like Ethernet IP or Modbus to name a few or using a collection of analog and digital signals. I prefer a combination of the two ideas. For command and control signals I use analog or digital signals. For all other data I use a communication protocol. The reason is that any decent technician can troubleshoot an analog or digital signal but troubleshooting a communication protocol takes a ver ...

Bearing Failure in VFD Coupled Induction Motor

Saturday, October 22, 2016

Operating on a VFD means there is a LOT of high-frequency distortion of the waveform, leading to imbalance in the magnetic circuit - which in turn leads to the development of shaft potential. If the shaft is higher potential than the ground plane, then current will flow - directly across the bearing, usually. So get a good grounding method (actual brushes riding on the shaft are by far the best over the long haul, in my experience). How do you know it's happening? The failure mode is scoring, ...

Difference between VSD, VFD, ASD, AFD

Wednesday, October 12, 2016

The most correct term - according to IEEE and IEC - is ASD (Adjustable Speed Drive). This refers to the electronic equipment used to regulate the operating speed of the motor and driven equipment by controlling the frequency and voltage applied to the motor.

NOTE that other terms in common use include (but are not limited to): VSD (Variable Speed Drive), AFD (Adjustable Frequency Drive), and VFD (Variable Frequency Drive), they are referring to the same motor drives, just different ...

Limitations of increasing motor speed

Monday, September 19, 2016

The normal frequency in Australia is 50 Hz and a client of mine runs his compressor motors up to 60 Hz which gives him greater output. But he only gets away with it because the machines are from the United States and are rated to operate at 60 Hz. Be careful because there could be a significant increase in power at the higher speeds in 60Hz.

Before you attempt to do this verify with the compressor motor manufacturer if you motor is VFD rat ...

VFD motors are a sales gimmick

Sunday, September 11, 2016

A VFD-driven general purpose motor can overheat if it is run too slowly. (Motors can get hot if they’re run slower than their rated speed.) Since most general purpose motors cool themselves with shaft-mounted fans, slow speeds mean less cooling. If the motor overheats, bearing and insulation life will be reduced. Therefore there are minimum speed requirements for all motors.

General purpose motors can be run with VFDs in many applications; however inverter-duty motors are de ...

Can we convert normal induction Motor to VFD purpose?

Thursday, September 1, 2016

To cope with the effect of the power electronics and the pulse thereof, it is usual to wind stator with specially varnished wire from supplier. This is often referred as triple coated as opposed to double coated (Standard offering). Don't be confused by number of coatings terminology. The wire has multiple coats applied. The term double and triple are generic to the industry. In effect the number of pin holes per m length of wire is reduced and the insulation (Enamel coating) on the wire has ...

VFD driven motor temperature gets raised

Tuesday, August 16, 2016

Case: A fan motor of 315kw running on VFD. Its operating speed is 795 rpm but its winding temperature gets heated like R phase temperature is 126.3 Y phase temperature is 125 and B phase temperature is 120. The motor is surrounded by cooling fans still temperature gets raised. Is there any alternative or have to change the motor to 400kw?

Heating effect can be caused by improper load match of the motor and mechanical VFD. Look at the temperature rise of the motor on the na ...

Can I run the motor higher than 50Hz by using a VFD?

Monday, August 8, 2016

All driven loads have some relationship between power and speed. As a general statement - more power is consumed at higher speeds.

Most motors are designed to operate at a constant speed and provide a constant output; however, modern technology requires different speeds in many applications where electric motors are used. A variable frequency drive (VFD) is a device that regulates the speed and rotational force, or output torque of mechanical equipment. Effects of applying VFDs are ...

Can capacitors in VFD contribute to improve power factor?

Wednesday, July 27, 2016

Capacitors inside the variable frequency drive (VFD) is mainly used to maintain the DC voltage, this is common thing all are well known about this, but power factor is mainly improved due to the cosine angle between voltage and current are mostly near to each other, however the inductive load produces the reactive power which will directly affect the wave form of input of VFD sine wave when we used additional filter ca ...

Why using PID Control on VFD?

Sunday, July 17, 2016

This question is for developer or those who are master in PID control & would like to save cost in certain application. For speed control, it's no longer used PID methodology by programmer. Now PID control is integrated into variable frequency drive control. For example, if you want to stabilize the speed at 1500rpm, no matter load changed, via an advanced VFD, PID is itself tuning to keep it stable at 1500rpm.

I like the auto tuning function on rotating equipment that has hig ...

Conveyor Belt Speed Issue

Friday, July 15, 2016

Q: I have a conveyor application. There we have a Motor connected to Gear Box. Motor is driven by a variable frequency drive (VFD). Details are as follows
Motor Power - 2.2 kW, 415V, 50 Hz, 1460RPM
VFD - 2.2 kW
Gear Box - Ratio = 58.25, RPM - 25 Rev/Min ,

According to the Above details, gear box output is 25 Rev/Min When the Motor Runs at 50 Hz at 1460 RPM. But I need to increase the Gear box output (Conveyor Speed) from 25 RPM to 53 RPM. So, as a t ...

VFD Altitude Derating

Monday, July 11, 2016

VFD derating is a manufacturer requirement when equipment ambient temperature is above 40 C degrees OR when equipment site is above 3000 feet in altitude. It is clear for manufacturers and engineers to avoid temperature derating by having the VFD's ambient temperature not to exceed 40 C degrees. On the other hand, VFD's manufacturers claim on altitude derating is due to thinner air at higher altitude that compromises the heat dissipation from the electronics. Although, it is a real claim, man ...

Overspeeding Motor with Variable Frequency Drive

Thursday, May 12, 2016

Over speeding the motor with a variable frequency drive will depend a lot on the existing load on the motor. If it is a fan load and you are currently at 100% of NP rating, you have no head room left to play with. If you have a roll spinning lightly loaded you will have much more head room. In some applications we run 240vac motors on a 480vac VFD and over speed from 60 Hz rated to 90 Hz- and develop 1.5 x the HP at rated torque. If you have a 480vac ...

How can We Manage VFD Torque Control?

Sunday, April 24, 2016

How can I control through the VFD Torque for a motor as I have a pump motor of 110 KW of rated current 200A controlled by Soft Starter and during the actual operation it consumed only 65 KW with 98A so I want to change this motor with another one lower in KW with VFD to control at the new motor Torque, so how to do that?
If the new motor is large enough to provide the load requirements then reducing the motor size will not affect performance. It is the load that dictates torque required ...