Chaps,
Is it possible to calculate the VA (apparent power) and the VAr (reactive power) of a three phase induction motor by using information from the manufactures data sheets?
I've tried it but must be doing something wrong because when I plot these values on a power triangle I'm getting a...
I have a question regarding dual voltage motors. Commonly 3 phase low voltage motors sold today (in Europe) are specified as 230/400v delta/star. According to my understanding if this motor was installed in the UK it would have to be configured to run in star. If it were configured to run in...
Chaps, just a quicky. Am I right in thinking that on a three phase motor's nameplate the full load amps is refering to the current drawn on each individual phase?
Thanks
Hi Chaps
I have a small test rig consisting of an SLC-500 rack, a small three phase motor driven by a VFD, and an optical sensor reading a slot in a disc mounted to the motor shaft. I have written a small ladder program to count the pulses for a period of time using a free running timer then...
Hi All
I teach at an engineering academy and one of the courses we offer is an introduction to PLC's. I have 8 Allen Bradley SLC-500's and use 8 paid for licences of RSLogix version 7.30.10. I recently obtained a budget to upgrade our old desktop PC's and specified Windows 7 operating system...
I wanted to demonstrate the voltage phase shift between primary and secondary on a three phase transformer so I had one built by a local company. All the winding ends are accessible so I can configure it any way I please.
When connected up as star-star I expected there to be no phase shift but...
I have a small three phase test motor and on the nameplate it gives a power factor of 0.77. This equates to an angle of around 45 degrees. I hooked the motor up to an oscilloscope and measured around 4mS difference between the voltage and current.
Four milliseconds equates to around 72 degrees...
Hi Chaps
I know that the power factor in a system is the ratio of KW to KVA but is it also true that the power factor equals the cosine of the angular displacement of voltage to current in a reactive circuit?
Thanks
I’m doing a simple experiment to measure the ac current thru a coil and I’m getting nowhere close to the calculated values. The coil is hand wound and has a value of 57mH when measured by an LCR meter. It also has a resistance value of 2.61ohms measured by the same meter. My power supply is...
We have an old Reyrolle S36A circuit breaker which the specs say is rated at 11KV 800A 500MVA. Just doing the math with these numbers they don't seem to add up. From memory VA = Vline x I x root 3. If you put the numbers in it seems like the breaker is rated at: 11000 x 800 x 1.732 = 15.24 MVA...
I have a three phase HV delta LV star connected transformer (Dy11). The name plate gives the following information: 400KVA rated, HV is 3.3KV at 70 amps, LV is 433v at 534 amps. My question: is the current on the name plate total three phase current, or is it current per phase. Simple for you...
