Hi Dears,

Can you help me to make a phase sequence indicator for 3 phase ac supply? i got some circuits and it is belongs to 60 Hz. Ineed a circuit for 415V, 50 Hz ac supply.

Bashi

 

The frequency will probably not make any difference. The voltage might be important, though.

Can you post your circuit?

 

http://webspace.webring.com/people/gl/lemagicien/elecpage/3phase/3phase.html

This shows the construction and how to adapt it for higher voltages.

In the equation to find the capacitor value, replace f with the frequency you wish to measure.

so for 50Hz measurements, f=50

Measure the ohmic resistance R of the bulbs. The condition to fulfill is that the three reactances must be equal, so the reactive capacitance should be:

XC = R and Xc = 1 / (2. pi . f . C ) from which :

C = 1 / ( 2. pi . f . R)

with R in kohms, C in microfarads and f = 60 Hz , we have the capacitor's value:

C [uF] = 1 / ( 0.12 pi R ) = 2.65 / R [kohm]

 

thank you RM,
We have recently (last two years) started using the 3-phase Zapi AC1 inverter and weening away from the DC Curtis Sepex system on the electric drive units we build.
During training on these units I use a scope to demonstrate the 3-phase output to the drive motors. It has been asked how do we figure which line is first, second and third. With the scope it is simple. I always said I would get back to them with a simple, non-scope method.
I always meant to research ways to determine the phase sequence but other more prioritized matters took me away from it.
Thank you for the input and link. It saved me the time and effort of research.
I have had my head up the proverbial digital ass for so long now that many things are slipping away.

I have 3-phase entering my home shop so this afternoon I am going to give this a whirl. If there are no more posts from VoodooMojo after this one (a pleasurable thought to some I am sure) then the experiment went awry. The obit will be in the Baltimore Sun.

Edit:
I must also thank Bashi for originating this post....

 

Uh, oh. You should set up your AI to post for you while you explore the great beyond.

Any whooz.. The phase indicator works nicely. It trick is getting inefficient bulbs. Both of them light, the brighter is the one that indicates direction. You can use a comparator and ADC to digitize it, i suppose.

Be careful on that 3 phase....Ill be checking the B-MoreSun.

 

well, what I cobbed together worked good enough ( I know that goes against your tag Bill ) but promising, so I will take the time to improve it.
I will digitize it as you suggest and it will become a piece of test gear.
A selection of different voltage caps and bulbs and I will be in business.
Then it will NOT be the enemy of the best!

Thanks again RM.

 

Not a problem. Any thing to help not be the enemy of the best.

 

The frequency will probably not make any difference. The voltage might be important, though.

Can you post your circuit?

Thanks, and see this attached circuit, here i am in confuse that what should be the wattage ratings of the resisters and voltage ratings of the capacitors.

 

thanks rm,
your suggestion will work but i need some portable phase sequence indicator.

 

Thats as portable as it gets. It is very small. You can make it 2 inches by 3 inches.

 

To Bashir,

thanks rm,
your suggestion will work but i need some portable phase sequence indicator.

A proper portable phase indicator is actually a very small(tiny) three phase motor with a rotating disc attached to the shaft to indicate direction of rotation. They are small and very common and used extensively in power industry, for a good reason.

Best of all, they are inherently fail safe. Any internal failure or lead or external problem would means the meter doesn't rotate. So there is no possibility of wrong phase sequence indication.

With phase shifting networks as shown in your attached circuit, component failure, connection failure or lead failure would result in possible wrong phase sequence indication. The consequence can be deadly not to say equipment damage to the least.

Please take this into account when you are actually committed to use this circuit.

Simulation shows that that the circuit can work:

1. if the phases are connected properly
2. the component are rated correctly

There are several hundred volts across resistors and capacitors and thus a warning has been placed on the requirement of the components. Most common capacitors and resistors available in the electronic market are not rated to operate at such high voltage level from 3phase 415V.

Using any such underrated component to build the above circuit would have deadly consequence.

The simulation is provided for educational purposes of how the circuit behaves and is not a recommendation for anyone to build and use one in actual power network.