Phase Shift – What Is It? – Explained
Phase shift occurs when multiple power feeds to a building are imbalanced, necessitating identical harmonic waves and phase rotations among transformers. A single supply poses no issues, but multiple supplies must be correctly aligned to avoid critical power problems. Installation of N+1 UPS systems must ensure no phase shift exists between two grid supplies. If phase shift is detected, downstream equipment may suffer from power issues. The solution involves locating and repairing the source of the phase shift, which may require significant upgrades to the infrastructure to prevent serious consequences.
Phase Shift happens what there is more than one power feed coming into a building and there are not balanced. The harmonic wave for each of the electrical supplies coming from each transformer must be identical. Each transformer supply needs to have the same phase rotation and the identical phase location. (zero) If there is only one supply coming into the building, then there is no issue. Phase shift can only occur when multiple supplies have not be correctly balanced and this will lead to critical power issues if not rectified.
On the other hand, if you have two supplies, then these need to be checked at the point of installation & need to be set up to ensure NO phase shift between them.
When installing N+1 UPS systems being feed by TWO Gird supplies via TWO transformers it is essential that the building management have already ensured that the phase rotation is the same for both in coming supplies and that there is no phase shift between the supplies.
What if you find out there is phase shift?
Then the power harmonics will be out and the wave form disputed, causing down stream power issues to equipment within the Data Centre
Watch the video which will explain the issue of phase shift and the dangers that it will create.
Example photo – These wave forms Should be identical – NOT like this image:
The wave form for the two supplies should look like this.
Image of Phase Rotation after works.
Phase shift Solution?
Find where the phase shift has happened. The transformer? Ring Main? LV panels? Locate it. Prove it. And then repair the issue, as soon as possible.
This may require major infrastructure upgradeworks but this is a necessity and needs to be carried out withimmediateeffect toavoidcatastrophe.
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