Variable Power Factor as a Load
Variable Power Factor as a Load
(OP)
I need to simulate a load with variable power factor for testing purposes. Aside from using cap banks and inductors , I am thinking to use a Synchronous Generator and a voltage regulator to do this. There are couple issues that I appreciate your feedbacks.
1) Is this option feasible?
2) How much variation of power factor do I get.
3) Is reactive power control different from voltage control?
4) Does anybody know of manufacturer of controllers with least expensive parts?
Thanks
1) Is this option feasible?
2) How much variation of power factor do I get.
3) Is reactive power control different from voltage control?
4) Does anybody know of manufacturer of controllers with least expensive parts?
Thanks






RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
The power factor of a motor will vary as the load changes. The VARs remain relatively constant.
You can supply varying Capacitive VARs by connecting a capacitor bank to the output of an auto-transformer. (Variac)
Inductive VARs may be a challenge. I would look for an old, large motor with a poor power factor. For example a 5 kW motor with a rated power factor of 0.9 will draw about 0.97 VARs. If you spin this up to synchronous speed with a smaller motor that is a little over belted the current draw will be almost purely inductive. Again you may vary the vars by varying the applied voltage with an auto-transformer.
Bill
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"Why not the best?"
Jimmy Carter
RE: Variable Power Factor as a Load
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
What I trying to do is just to introduce a load with varaible power factor for a device that checks this variation.
One way is to switch on and off cap banks and reactors in parrallel to obtain this, I remember from school that by varying filed voltage I could vary the power factor and therefore I decided to look into this.
I found " Hurst manufacturing " and " Dayton" supplier for these motors.
So a 120V/ 1 HP/ AC motor I thought would do the trick with a controller to change the field voltage!!
I didnt think I needed load, and I wanted to turn this without load.
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
Back to basics..using capacitors and inductors.
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
You can put a resistance (a heater) and utilize the motor only for controling reactive power in parallel with the resistance.
RE: Variable Power Factor as a Load
How about using a single phase synch. motor and another motor as a load, then by varying speed on Dc motor I will introduce different load and by varying field voltage I can change pf seen through synch. motor.
RE: Variable Power Factor as a Load
RE: Variable Power Factor as a Load
Use an auto transformer feeding an induction motor to supply and vary the VARs. You may have to use a second motor to spin the VAR generating motor at low voltages.
The auto transformer will be in parallel with the resistive load bank.
Set he resistive load bank at the kW load you want to test at. Than vary the voltage to the motor to vary the VARs. The power factor will respond to the ratio of kW and KVA.
The VARs developed by the motor will reflect through the auto-transformer and vary your power factor.
Disconnect the start circuit of the motor you will use for the VAR generator and spin it with a second motor.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Variable Power Factor as a Load
I am not sure about using the second motor.What I understood is for example lowe the voltage to half and then have the second motor coupled with this motor spin it at full speed?
What do I gain with this?
RE: Variable Power Factor as a Load
To get a lagging PF I'd use the same variac powering a transformer which has its secondary shorted.
Off course you also need some resistane in the load for a few watts to flow.
RE: Variable Power Factor as a Load
Then I would have two different voltage levels in parralel!
RE: Variable Power Factor as a Load
If you have a large transformer available, it may be used instead of the motor as per sibeen's suggestion.
The air gap in the motor demands many more VARs per inch than iron and as a result a motor can be expected to absorb more VARs than a transformer of similar kW rating.
But when you compare the cost of two motors to the cost of a larger transformer it may be feasible. And if you have a suitable transformer available, by all means use it.
Thanks sibeen.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Variable Power Factor as a Load
Unfortunately the neurons in my brain that hold the name of that company died. I seem to remember that the Name begins with and "H", though.
old field guy
RE: Variable Power Factor as a Load
Your Cadillac solution sure trumps my compact solution. It stimulated some neurons and brought back memories of some training stints a long time ago.
Your post solidified a thought that was running around in the back of my mind and compelled me to Google.
tctctraining;
See
htt
if the budget will handle it, consider this equipment.
Bill
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"Why not the best?"
Jimmy Carter
RE: Variable Power Factor as a Load
I restarted those neurons a split second before reading your post.
Yes, those are the people.
I had the good fortune to have access to a very complete set of their training aids at one time and I used the synchronous motor to demonstrate power factor correction using over-excitation and other operations.
This IS the top-line set-up for demonstrating various electrical power devices.
old field guy