电气试验
一、试验基础 | Testing Fundamentals
二、绝缘试验 | Insulation Testing
三、变压器试验 | Transformer Tests
四、开关设备试验 | Switchgear Tests
五、保护与控制试验 | Protection & Control Tests
Transformer Acceptance Testing — From TTR to SFRA
Fang, we're doing the full suite of acceptance tests on the main power transformer today — 100 MVA, 230/34.5 kV. Let's follow the ITP exactly. What's first?
方工，今天做主变压器全套交接试验——100 MVA、230/34.5 kV。严格按 ITP做。先做什么？
方工: First — visual check and mechanical inspection. Bushings intact? No oil leaks? Cooling fans working? Tap changer position correct? All checked. Now the electrical tests.
首先——外观检查和机械检查。套管完好？无漏油？冷却风扇正常？分接开 关位置正确？全部检查完了。现在电气试验。
Test 1: TTR — turns ratio test. We'll measure the voltage ratio at every tap position. For the nominal tap, the ratio should be 230 kV / 34.5 kV = 6.667. IEEE allows ±0.5% deviation.
试验1：TTR变比测试。每个分接位置测电压比。额定分接变比应为230 kV / 34.5 kV = 6.667。IEEE允许±0.5%偏差。
试验技术员: 接线好了。高压侧注电、低压侧读数……额定分接：6.668——偏差0.015%。 分接1 (+5%): 6.994, 分接3 (-5%): 6.341。全部在公差内。
Connected. Injecting on HV, reading on LV... Nominal tap: 6.668 — deviation 0.015%. Tap 1 (+5%): 6.994, Tap 3 (-5%): 6.341. All within tolerance.
方工: Test 2: winding resistance. We measure the DC resistance of each winding — this detects loose connections or broken strands. HV winding: target 0.85 ohms ±5%. Actual: Phase A 0.84, B 0.86, C 0.85 — all within spec. LV winding also passes.
试验2：绕组直流电阻。测各绕组直流电阻——检测松动连接或断股。高压 绕组：目标0.85欧姆±5%。实测：A相0.84、B相0.86、C相0.85——都在规格 内。低压绕组也通过。
What about the insulation resistance and PI?
绝缘电阻和极化指数呢？
方工: Test 3: Insulation resistance. Using a 5 kV megger. HV to LV and ground: 12,500 megohms at 60 seconds. The polarization index — R60/R15 ratio — is 2.8. IEEE requires PI >2.0 for Class A insulation. Excellent condition.
试验3：绝缘电阻。用5 kV兆欧表。高压对低压及地：60秒12,500兆欧。 极化指数——R60/R15比值——2.8。IEEE要求A级绝缘PI>2.0。状态极佳。
Test 4: Tan delta — dissipation factor. At 10 kV, tan delta is 0.22%. Spec is <0.5% for new transformers. Pass.
试验4：介损tan delta。10 kV下介损0.22%。指标是新变压器<0.5%。 通过。
Test 5: SFRA — sweep frequency response. This is the fingerprint test. We sweep from 20 Hz to 2 MHz and compare the response to the factory SFRA. If there's any winding displacement or damage, the curves won't match.
试验5：SFRA频率响应分析。这是指纹测试。从20 Hz扫到2 MHz，跟出厂 SFRA波形对比。如果有绕组移位或损伤，曲线就对不上。
试验技术员: SFRA做完。覆盖在原厂曲线上面——HV、LV、HV-LV三条响应基本重合。偏差 在低频段小于1 dB，中频段小于0.5 dB。没有任何机械问题。
SFRA done. Overlay with factory curves — HV, LV, HV-LV all three traces nearly identical. Deviation <1 dB at low frequencies, <0.5 dB at mid frequencies. No mechanical issues.
Excellent. All acceptance tests passed. This transformer is cleared for energization.
非常好。全部交接试验通过。这台变压器可以送电了。
Breaker Testing — Timing, Contact Resistance, and CT Injection
Now testing the 34.5 kV feeder breaker — VCB type, 1,250A, 25 kA. Let's start with contact resistance.
Micro-ohmmeter connected — 100A test current through main contacts. Phase A: 12 µΩ, Phase B: 14 µΩ, Phase C: 11 µΩ. Spec is ≤25 µΩ. All pass.
Next — mechanical characteristics and timing. Connect the breaker analyzer. We measure close time, open time, and three-phase simultaneity.
Close command — close time: A 47ms, B 48ms, C 46ms. Non- simultaneity is 2ms — well under the 5ms spec. Open times: 26-28 ms, non-simultaneity 2ms. Spring charge motor current is within normal range.
Next we do CT circuit injection. This feeder has protection- class CTs, 800:5 ratio, C200 class. Let's do the excitation curve first — check the knee point voltage.
OK. Inject voltage on the secondary, measure excitation current. Knee point at 210V — above the C200 requirement of 200V. Pass. Now primary injection — using the primary injection set to inject 800A through the CT primary, measure secondary current.
Primary injection 800A... secondary current: 4.98A. Theoretical: 5.00A. Ratio error: 0.4% — within ±1% spec. Polarity is also correct — protection direction is right.
Perfect. The CT circuit is continuous from primary all the way to the protection relay terminals with correct polarity. This feeder breaker is ready for service.