Complete Analysis of Current Transformer Nameplate (LB6-132W3)

Current Transformer Nameplate

🔌 Complete Analysis of Sieyuan Current Transformer Nameplate (LB6-132W3)

About This Article: This comprehensive guide explains every detail found on a high-voltage current transformer nameplate, essential for electrical engineers, substation operators, and power system professionals.

1. Manufacturer Information

Brand

Sieyuan (思源)

Company

Jiangsu Sieyuan Hertz Instrument Transformer Co., Ltd.

Country

China

Manufacturing Date

July 2018

Serial Number

131811717

2. Basic Technical Specifications

Type Designation: LB6-132W3

This designation indicates a 132 kV class outdoor current transformer designed for high-voltage transmission applications.

Standard Compliance

IEC61869-2:2012

International standard for instrument transformers

Rated Frequency

50 Hz

Standard power system frequency

Maximum Altitude

1000 m

Installation height limit for rated performance

Installation Type

Outdoor

Weather-resistant design

3. Insulation Levels (145/275/650 kV)

These three critical values define the transformer's insulation capabilities:

Parameter	Value	Description
Um	145 kV	Highest system voltage (Maximum operating voltage)
BIL	275 kV	Lightning impulse withstand voltage (Protection against lightning strikes)
SIL	650 kV	Switching impulse withstand voltage (Protection during switching operations)

4. Secondary Winding Configuration

This current transformer features 5 independent secondary cores, each designed for specific applications:

Terminal Marks	Rated Output (VA)	Rated Current Ratio	Accuracy Class	Application
1S1-1S2	10 VA	1000/1 A	5P15	Primary Protection
2S1-2S2	10 VA	1000/1 A	5P15	Primary Protection (Duplicate)
3S1-3S2	10 VA	1000/1 A	5P25	Backup Protection
4S1-4S2	10 VA	1000/1 A	0.5	Metering and Measurement
5S1-5S2	10 VA	1000/1 A	0.2S	Revenue Metering (High Precision)

Understanding Accuracy Classes:

• 5P15 and 5P25: Protection class - designed for relay protection with composite error limits of 5% at 15x and 25x rated current respectively
• 0.5: Metering class - ±0.5% accuracy for general measurement purposes
• 0.2S: Special metering class - ±0.2% accuracy for revenue-grade billing (highest precision)

5. Short-Circuit Performance

These parameters ensure the CT can survive fault conditions without damage:

Thermal Current (Ith)

40 kA / 3 seconds

Maximum RMS current the CT can withstand thermally for 3 seconds during short-circuit

Dynamic Current (Idyn)

100 kA

Peak current the CT can withstand mechanically (typically 2.5 × Ith)

Note: The dynamic current represents the maximum instantaneous current the transformer can handle without mechanical damage to its internal structure.

6. Physical Specifications

Oil Weight

120 kg

Insulating oil for cooling and insulation

Total Weight

520 kg

Complete assembled weight

Construction Type

Oil-Immersed

Uses oil for insulation and cooling

7. Winding Diagram Explanation

The nameplate includes a schematic showing the internal connection arrangement:

• Primary Terminals: P1 and P2 - connected to the main power line carrying 1000A
• Secondary Cores: Five separate cores labeled 5S, 4S, 3S, 2S, and 1S
• Series Connection: Cores are arranged with a combined rating of 1000A
• Parallel Configuration: C1-P1 and C2-P2 connections shown

⚠️ CRITICAL SAFETY REQUIREMENT:
The arrangement of secondary windings requires that THE END SCREEN MUST BE EARTHED IN OPERATION! This is mandatory to prevent dangerous voltages on secondary terminals and ensure personnel safety.

8. Application Context

This current transformer is typically deployed in:

• 132 kV transmission and distribution substations
• Line protection and differential protection schemes
• Multiple protection zones with different sensitivity requirements
• Revenue-grade billing measurement systems (using the 0.2S core)
• SCADA and remote monitoring systems
• Synchrophasor measurement units (PMUs)

Why Multiple Cores? Different applications require different accuracy levels and burden capacities. Protection relays need fast response but can tolerate higher errors at normal current, while revenue meters require extreme accuracy but only at rated current. Having dedicated cores optimizes performance for each application.

9. Key Safety and Installation Guidelines

⚠️ CRITICAL SAFETY INFORMATION:

• Never open-circuit a CT secondary while primary current is flowing - this can generate lethal voltages
• Always ground one point of each secondary winding to prevent dangerous potential buildup
• The end screen MUST be earthed during operation (as noted on nameplate)
• Use proper polarity when connecting to protection and metering devices
• Do not exceed the rated burden on any secondary core

Installation Considerations:

• Ensure proper vertical alignment and mechanical support for the 520 kg unit
• Verify oil level and quality before commissioning
• Test insulation resistance and turns ratio before energizing
• Check all secondary connections for proper polarity
• Implement proper cable routing to avoid induced errors

10. Summary and Technical Significance

The Sieyuan LB6-132W3 is a sophisticated, multi-core oil-immersed current transformer designed for comprehensive protection and metering in high-voltage substations. Key highlights include:

• ✅ IEC61869-2:2012 compliance - meets international standards
• ✅ Five independent secondary cores - optimized for different applications
• ✅ High short-circuit withstand capacity - 40 kA thermal, 100 kA dynamic
• ✅ Revenue-grade accuracy - 0.2S class for precise billing
• ✅ Robust construction - outdoor-rated, oil-immersed design
• ✅ Proven Chinese technology - manufactured by established company

About esbangla.com: This article is part of our comprehensive electrical engineering knowledge base, providing detailed technical information for power system professionals in Bangladesh and beyond.

Related Topics:

• Current Transformer Testing and Commissioning
• Protection Relay Settings for 132 kV Systems
• Understanding CT Accuracy Classes
• Substation Equipment Maintenance Procedures