چه تیستە سەریکەییەکان دەبێت ڕووبدەرە بەشداری بگرن؟
Hiştî hemû, minam Oliver, û çendê tê de qadimiyek bimeyên instrument transformer da kêmê sê deqên pir hene. Ji naverokê yekê werin ku ew di navbera xwe de çareseribûn, min li ser dêhatiyan sifir yên pêk hatîn.
Yewa, dibe mi bi wê re berdareve bibînim: Peyvên cîhek derbasdar combined instrument transformer parastînin an dest pêkirin? Herçî ew têke ji xebatên herêmî yên jînra elektrîk ên piştgiriya xwe ye — tu nekêne wekî ku heta nezîk bike.
1. Testî Insulation: "Peyvên Parastina" ya Bêgara?
Yekem û mîna herêmî, testa insulation performance hene. Combined instrument transformers lêgerîn di tenê vêje 35kV de bikin. Ger insulation nebe standart, dikarin wanê ji xebetên hesabkirina nedîsa be tekerdena an dinbûnê bigere.
Dikarin testên sereke:
Testa resistance insulation – bi karîna megohmmeterî testa resistance insulation yên navbera windings bikin, ku divê li ser 1000MΩ be.
Testa withstand voltage power frequency – simulasyonan ve şertên voltage extreme bikin ra dîtin êger transformer di demekê xotî de voltage surges ji bo level rated yekê girîng bikin.
Testa partial discharge – bi karîna wisa dikarin xebetên navendî yên binnayîn, wekî bubbles an cracks, bigerin, ku dikarin di dema operasyonê mezin de çavkanîn.
Yewa, min bi komplâna customerê re saz kir, ku transformer di demekê mînan de xebet çê. Rêzikî rastî bêgara treatment insulation hene. Berdanî, ev rêzik nabe!
2. Testa Ratio and Error: Accuracy Is the Key!
Yekanên core yên combined instrument transformer accurate measurement current and voltage hene, ku yana ratio precise be, û error within standard limits be.
Dikarin:
Testa ratio – verifying that the voltage and current ratio between the primary and secondary sides matches the design specifications.
Error test (ratio error and phase error) – especially for metering-grade transformers, the error must be controlled within ±0.2%.
Ji kerema xwe, customers say things like, “My transformer looks fine, but the electricity bills never match.” That’s when we usually suspect the error has exceeded acceptable limits. So this step directly affects the user’s interests.
3. Polarity Test: If the Direction Is Wrong, Everything Goes Wrong!
Don’t underestimate this step — the polarity test is really important. If the polarity of the transformer is reversed, it can cause the protective relay to misjudge and even disable the entire protection system.
We use either the DC method or AC method to confirm the polarity of the transformer. Especially for combined transformers, which contain both voltage and current components, the polarity must match exactly — otherwise, the whole system could fail.
4. Volt-Ampere Characteristic Test: The “Ultimate Challenge” for Current Transformers
This test mainly applies to the current transformer part. The volt-ampere characteristic reflects the magnetization performance of the iron core and helps us determine whether the transformer can function properly under fault current without saturation.
We gradually increase the voltage, record the current changes, and draw the volt-ampere curve. If the curve is abnormal, it indicates there may be a problem with the core, and the unit needs to be sent back for repair.
I remember a project where the customer reported that the protection system kept malfunctioning. After checking the volt-ampere curve, we found the core was already severely saturated — that was the root of the problem.
5. Short Circuit and Open Circuit Test: Simulating Extreme Conditions
To verify the transformer’s performance under abnormal conditions, we also perform:
Secondary short circuit test – checking the protection performance of the voltage transformer when the secondary side is shorted.
Secondary open circuit test – observing whether the current transformer generates overvoltage when open-circuited.
These tests aren’t part of the regular routine, but they are essential for special applications, such as important substations or new energy grid-connection projects.
6. Temperature Rise Test: Can It Handle the Heat?
During long-term operation, instrument transformers will generate heat. If the heat dissipation design is poor or the materials can’t withstand high temperatures, it could lead to insulation aging or even burnout.
We simulate rated or even overloaded conditions and measure the temperature rise across different parts to ensure it stays within acceptable limits.
This test is especially important in high-temperature environments or areas with high load demands.
7. Sealing Test (for SF6 Transformers)
For SF6 gas-insulated combined instrument transformers, the sealing test is a must. If the gas leaks, it not only affects insulation performance but also causes environmental pollution and can even endanger personal safety.
We use infrared imaging leak detectors or gas leak detectors to thoroughly inspect all sealing surfaces and weld points.
8. Appearance and Structure Inspection: Details Make the Difference
Don’t think this is just superficial — the appearance and structure inspection is actually very important. We check:
Whether the housing is deformed or cracked
Whether the terminal connections are tight and clearly marked
Whether the nameplate information is accurate
Whether the installation structure is reasonable
Once, we found a loose grounding terminal on a transformer. While it might seem minor, if it goes unnoticed and is put into operation, the consequences could be serious.
Conclusion: Being Qualified Is Not the Goal — Safety Is the Foundation
As someone who has worked in the instrument transformer industry for eight years, I know firsthand that behind every qualified combined instrument transformer are layers of strict testing. Each test isn’t just a formality — it ensures that the equipment can operate stably, safely, and reliably in real-world conditions.
If you're in the industry, I hope this article helps you organize the testing process. And if you're a client or engineer, I hope it gives you a better understanding of what goes on behind the scenes with instrument transformers.
A qualified instrument transformer isn’t just about words — it’s truly “tested” into existence.
I’m Oliver — catch you next time for more instrument transformer insights. Bye!
