Blog Reading
Home » Blog » Questions » Checking phase sequence in synchronization operation

Checking phase sequence in synchronization operation

We know that the phase sequence is one of many conditions of the synchronization operation, and made in the beginning of construction. But if for any reason we need to check the phase sequence for two different sources of power. How to do that?

Sequence, or what we call positive sequence is a relative rotation for phases that we call as A-B-C, so positive sequence has this rotation. By convention this rotation in counter-clockwise.

If you are in a substation that is fed from 2 sources, making sure the sequence are the same is of primary importance.

You can not tell at the local substation what is the designated phase-A conductor from the two sources unless you visually confirm what is the phase-A conductor and trace it all the way back to the from source to destination, or as an alternative, ring it out.

Many utility require that all phase-A, Phase-B and Phase-C are matched in all subs.

The above is not required if all you want to do is to ensure phase sequence are the same so that 2 sources can be synchronized successfully.


A-B-C can be synchronized to A-B-C
A-B-C can be synchronized to B-C-A
A-B-C can be synchronized to C-A-B

So what we have above is positive sequence can be synchronized to positive sequence, the rotation needs to be the same.
You need a phase angle meter a reference 3-phase VT or CVT set. This voltage reference set, must be able to be energized from the two sources separately. Connect channel one of the meter to Van and channel two to Vbn. For delta connected VT, connect channel 1 to Vab and channel 2 to Vbc.
Apply power to the VT set and measure the phase angle and record. Now deenergize, isolate the first source and energized with the other source.

Same angle = same sequence
Different angle = u have a problem!

You may also like:

Storage battery is an important component of UPS system. Choosing battery is not only related to the cost of the manufacturers, but also affecting the reliability of continuous power supply of UPS power. ...
For cable lengths up to 100 meters (and motor suitable for inverter applications) it is not necessary a filter; for lengths from 100 to 200 meters, a series reactance can be used; for greater lengths it is ...
AC drives are designed to provide variable speed control. They maintain the optimal speed required for an application to enhance production and save energy. Low- and medium-voltage drives gradually accelerate ...
AC Drives has to be selected by current and not power. That should be same but is not always. Immerged pumps for examples are using more current than standard ac motor for same mechanical power. In general ...
Noise and sound are a bit tricky to deal with. Generally the noise from the motor fan is "white noise" and not objectionable to the ear, except for large machines that were mentioned or as mentioned below. The ...
service The engineers in AC Drive China are very professional in Chinese automation industrial control fields, provide you comprehensive energy saving solutions.

Hot Tags


Frequency directly represents no of rotation of rotor for that machine, the higher the frequency the more the rotation of the rotor, i.e. the rpm of the motor there by result ... Due to power electronics technology and microelectronics technology rapid development, variable frequency drive reforms and upgrades speed also is faster, introduce new products, ... Since the 21st century, China variable frequency drive industry is highly fission. Many foreign brands begin to set up factories in China, the implementation of the localization ... My personal preference is for an AC line reactor simply because it does a better job of protecting the variable frequency drive from the line and the line from the drive. I've ... As nowadays there is a trend in green energy production and energy efficiency, what solutions/applications would you recommend in reduction consumed energy of a motor driven by ...

What's New