I am in need of a C++ library of OPC function calls. I also need example code. I need to transfer data using OPC between 2 PC's via Ethernet. Does anyone have any idea as to where I can purchase the library, with examples and good documentation? Thanks, rdrago
What is the point of installing VSD's on conveyor motors that will run only at 60HZ?
Would a "soft starter" be a better choice considering how VSD's can potentially damage non-inverter equipped motors even with the addition of dv/dt filters? Also, VSD's generate harmonics on the...
Thank you all for the comments. It is good advice that is well taken. I was very careful with the amp probe to make sure that the polarity and centering were correct.
I have another question concerning the same set of power measurements from this same motor/drive combination. I will describe...
Buzzp: You are right. I called the manufacturer and he said that the motor may have unbalanced current on the line side if the drive is not running at rated load. It is no problem.
Thanks for the help.
rdrago
Current measurements at the drive output are as follows:
Phase 1: 4.88A
Phase 2: 4.83A
Phase 3: 4.85A
As you can see, the motor load is balanced.
However, I am still wondering why the current at the input to the drive is so unbalanced. Readings are as follows:
Phase 1: 2.3A
Phase 2: 5.4A...
Thanks for the responses.
To buzzp: I did not measure the current on the load side of the drive because access was not easy. I will measure tomorrow. Today, I measured each phase current on the drive input individually using the 43B. Thanks for link.
To skiier: I am trying to get a handle...
A 20 HP, 3 phase, 480 volt motor is connected to a motor drive. The measured current (Fluke 43B) at the input to the drive is as follows:
Phase 1- 2.3A
Phase 2- 5.4A
Phase 3- 5.3A
Does anyone have any idea why the Phase 1 current at the input to the drive is so low? The motor and...
The jbartos site contains an excellent article on non-linear loads and their effect on the transformers that supply them. Since VFD's are non-linear as viewed from the power source, harmonic frequencies are generated that lower the power factor of the source at the drive input.
However, the...
I plan on using line reactors on the input side of the VFD and dv/dt filters on the output side. My existing cable runs average 300' from the proposed inverter to the motor. The existing motors are 1972 vintage 20 and 30hp models. Upon reading some of the historical postings on this forum...
Thanks to all for the information.
To wwilson: You offer good advice. The improvement in your power factor while using line reactors is impressive. The ABB ACS400 has a 3% line reactor feature although I'm not sure what 3% means at this point. Thanks again.
To wwilson: Renting is a really good idea. I'll try it. Thank you.
To pablo02: The motor shaft is connected to a fan that pulls air through a duct. The motors are not controlled. They run at rated speed and FLA. We regulate the amount of air that is pulled through the duct with a butterfly...
Thanks again to everyone for the responses.
To pablo02: Doesn't the reactive power delivered to the motor go through the drive? How can the utility see unity power factor? In response to your other question, we have 50 of these motors that need inverter drives.
To rbulsara: Am I trying to be...
Thank you all for your response.
To rbulsara: The factory pays for the reactive power even though it is returned to the source. Therefore, my thought was to measure the real and reactive power that is delivered to the motor in order to report the true savings in dollars. In my application...
How do I measure power in a 3 phase electric motor? I am trying to justify the installation of a drive on a motor based on the power savings obtained through the use of a drive. The motor is running a fan load. The problem lies in the fact that the power factor at different motor speeds...
