چی دەبێت پیشان بێت کاتێک ڕێژەگرە ناوەشووەکان هەڵبژێرین و سازنین؟
Halo hemûyan, min James im, da 10 salan henek çaliskiram le current transformers (CTs).
Lê jî ranin di cihanên xebatê de yên dest pê kirina vê yar, tênekirina wêşen û debugkirina pirantiyên, heye bêtirên projeyên substation û çareseriyên hêsan CTs — bi sah û îro dixwaz dikim bi outdoor current transformers da. û bêtir e, min çewtên kiribûm, wan çewtên bibûm û tevahî piçeyên dijîn dibûm.
Di rastan, di rojan de, yek inzîner mîna qeste:
“James, gava divê bêtirên outdoor CTs bike — tiştên xweyên bêtir ên hewce ne?”
Vê çewtê yeke çewtê pratîk! Naxsena, dibe dilam bi we bikin:
Divê tiştên sereke yên bi bîr bike biçavê ku hêj ji bo hilbijartina û nusandana outdoor current transformers?
Nisht terminolojiya teknîk bingehîn — tenê gotina hêsan bi 10 salan henek amadekirina min. Bi bîr bike!
1. Hilbijartina — Divê Ferîlê Bike, Ji Yekem Bi Bîr Bike
1.1 Xistîna Parametreyên Sistemê
Ev ê yekem guherbar — û herî serpil:
Çi primary current rated e?
Çi system voltage level e? Wese 10kV, 35kV, an 110kV?
Ji bo measurement, metering, an protection e?
Karên din derbendê accuracy classes û design requirements din. Mînak:
Metering CTs hewce ne high precision (tenê 0.2S an 0.5S);
Protection CTs zêde hewce performance during faults (wese 5P20 an 10P20).
1.2 Environmental Conditions Matter Big Time
Outdoor CTs li ser wind, rain, snow, sun, û temperature extremes.
Hebe salt spray corrosion? Tenê near coasts or chemical plants;
Hebe big temperature swings? Think -30°C in northern winters and +40°C humid summers;
Any vibration or lightning risk? These also affect lifespan and reliability.
So when choosing a model, go for:
Corrosion-resistant housing (stainless steel or fiberglass);
UV and aging-resistant insulation materials;
At least IP55 protection rating to block dust and water.
1.3 Pick the Right Structure Type
Common outdoor CT types include:
Bushing type – often used at transformer outlets;
Core-type (window-type) – common on overhead lines;
Post-type – used near GIS or circuit breakers.
Choosing the wrong type can lead to installation difficulties or even measurement inaccuracies and safety risks.
2. Installation — Small Steps, Big Impact
2.1 Grounding Is Non-Negotiable
The secondary side of a CT must be grounded properly — otherwise, an open circuit can create dangerously high voltages, risking both life and equipment.
In outdoor conditions with high humidity and frequent rain, poor grounding can cause:
Insulation degradation;
False trips;
Equipment damage.
So always:
Check that ground connections are tight and solid;
Test the grounding resistance;
Use anti-corrosion measures so the connection stays good over time.
2.2 Double-Check the Polarity
This is an old issue, but still a big one. Getting polarity wrong can cause:
Incorrect measurements;
Metering errors;
Protection misoperations — like tripping when it shouldn’t.
Especially in differential protection schemes, a reversed CT polarity can create abnormal differential currents and false trips.
Before installation:
Make sure P1, P2, S1, S2 markings are clear;
Confirm secondary wiring matches;
Perform a polarity test if unsure.
2.3 Seal It Up and Keep Water Out
Even though outdoor CTs have weatherproof ratings, improper installation can still let moisture in.
If not sealed well:
Internal insulation drops;
Terminals corrode;
Measurement becomes unreliable.
After installation, check:
All covers are tightly fastened;
Sealing gaskets are intact;
Cable entries are properly sealed against water.
2.4 Avoid Mechanical Stress
Some installers force the CT into place by pulling or twisting — this can deform internal parts and damage the unit.
Instead:
Use proper mounting brackets;
Adjust alignment before connecting;
Never use brute force to make things fit.
2.5 Testing After Installation Is a Must
Just because it’s installed doesn’t mean it’s done. You should still do:
Ratio test – confirm actual ratio matches nameplate;
Polarity test – double-check wiring direction;
Excitation characteristic test – especially for protection-grade CTs;
Insulation resistance test – ensure good insulation;
Load simulation test – run a quick check before full operation.
3.Final Thoughts
As someone who’s spent 10 years in the field, here’s what I’ve learned:
“Wrong selection means wasted effort; bad installation means hidden dangers.”
Whether you're new or experienced, when dealing with outdoor current transformers, you must treat every step with care and respect.
If you're just starting out, ask for help, read the manuals, and learn from those who’ve done it before. If you're seasoned, don’t get complacent — after all, safety comes first, and accurate data directly affects grid stability and cost control.
If you ever run into issues during selection or installation, feel free to reach out. I’m happy to share more hands-on experience and practical tips.
Here’s hoping every outdoor current transformer runs safely and accurately, protecting the power grid day and night!
— James
