LPIT — low-power instrument transformers for current and voltage in 145–420 kV GIS
LPIT (Low Power Instrument Transformer) is a low-power electronic instrument transformer for 145–420 kV high-voltage GIS. One unit combines a Rogowski coil current sensor and a capacitive divider voltage sensor. It is used in new and digital 110–400 kV substations built on the manufacturer's own GIS.
- Versions
- for GIS 8DN8 145/170 kV, 8VN1 145 kV, 8DQ1 420 kV, 8VQ3 420 kV
- Principle
- Rogowski coil (LPCT) + capacitive divider (LPVT) in a cast insulating partition
- Insulation level
- 145/275/650 kV … 420/650/1425 kV
- Thermal withstand
- 50 kA (3 s) … 80 kA (3 s)
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The low-power current transformer (LPCT) and low-power voltage transformer (LPVT) are built into a single cast insulating partition of the GIS. The device fully complies with the IEC 61869 series of standards and with IEEE C37.92. Analog signals go directly to protection terminals or to the merging units of an IEC 61850 digital substation. The saturation and ferroresonance typical of conventional CTs and VTs do not occur here.
With conventional transformers a GIS bay is longer and heavier. LPIT shortens it by about 30 % and cuts the weight by about 1500 kg, and it reduces the volume of insulating gas and the amount of cabling and installation work. Each bay has two current sensors and one voltage sensor, so the measurement is redundant. One device serves both protection and metering, and a single version suits all rated bay currents. Passive sensors in cast insulation are not affected by overvoltages. They are not disconnected during high-voltage tests of the GIS or the cable.
Versions are offered for 8DN8 GIS at 145 and 170 kV, Blue GIS 8VN1 at 145 kV, and 8DQ1 and Blue GIB 8VQ3 at 420 kV. Insulation levels cover the range from 145/275/650 kV to 420/650/1425 kV. Thermal withstand is 50 to 80 kA for 3 s, operating temperatures range from −30 (−50 for Blue versions) to +55 °C, and weight is 45 to 185 kg.
The rated primary current is 200 or 206 A. The measuring range is 200–3150 A for 145 kV, 200–4000 A for 170 kV and 206–6300 A for 420 kV. Current accuracy classes are 0.2S and 5P250–5P389 (5TPE on the analog output and 2TPM on the digital output), voltage class 0.2 P. The rated primary voltage lies between 66/√3 and 400/√3 kV.
SIPROTEC 6MU85 and SEL‑700MU merging units are compatible, as is any IED with LPIT/LEA inputs. Differential protection schemes are possible in which LPITs work together with conventional CTs.
Technical specifications
| Versions | for GIS 8DN8 145/170 kV, 8VN1 145 kV, 8DQ1 420 kV, 8VQ3 420 kV |
|---|---|
| Principle | Rogowski coil (LPCT) + capacitive divider (LPVT) in a cast insulating partition |
| Insulation level | 145/275/650 kV … 420/650/1425 kV |
| Thermal withstand | 50 kA (3 s) … 80 kA (3 s) |
| Current range | 200–3150 A (145 kV), 200–4000 A (170 kV), 206–6300 A (420 kV) |
| Accuracy class | 0.2S / 5P250…5P389 / 5TPE (2TPM); LPVT — 0.2 P |
| Weight | 45–185 kg |
| Standards | IEC 61869, IEEE C37.92 |
| Interface | SIPROTEC 6MU85, SEL-700MU and IEDs with LPIT/LEA inputs |
Replacement for
no direct analog; the closest are the built-in CTs and VTs of GIS (generic type)
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
LPIT — low-power instrument transformers for current and voltage in 145–420 kV GIS. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8504 31 29 00 |
|---|---|
| HS, 6 digits | 8504 31 |
| CN (EU) | 8504 31 29 |
| HTSUS (USA) | 8504 31 40 00 |
| China customs tariff | 8504 31 10 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
Which GIS are LPIT units made for?
For 8DN8 at 145 and 170 kV, Blue GIS 8VN1 at 145 kV, and 8DQ1 and Blue GIB 8VQ3 at 420 kV. Thermal withstand is 50 to 80 kA for 3 s.
Is LPIT suitable for revenue metering?
Yes, the current accuracy class is 0.2S and the voltage class is 0.2 P. The same device also serves protection, with classes 5P250–5P389.
Which merging units does LPIT work with?
SIPROTEC 6MU85 and SEL-700MU are compatible, as is any IED with LPIT/LEA inputs. Digital exchange follows IEC 61850.
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