USD
EUR
GBP
CAD
AUD
CHF
HKD
JPY
RUB
BRL
CLP
NOK
DKK
SEK
KRW
ILS
MXN
CNY
SAR
SGD
NZD
ARS
INR
COP
AED
Home
Products
Current Transformer
Three phase CT Protection Current Transformer High Voltage Current Transformer
Indoor current transformer Outdoor current transformer Indoor voltage transformer Outdoor voltage transformer
Summation Current Transformer Mini Current Transformer
Combined Current Transformer Loading-Type Current transformer Bus Bar-Type Current transformer Pin-type Current Transformer Current-Voltage Transformer DC Immune CT Voltage Power Transformer Zero-Sequence Current Transformer Special Current Transformer
Low Voltage Current Transformer
Residual Current Sensor
Flexible Rogowski coil
Split Core Current Transformer
Current transducer
Current Sensor
Closed Loop Hall Effect Current Sensor DC leakage current sensor Hall Effect Current Transmitter Hall Effect Voltage Sensor & Transmitter Open Loop Hall Effect Current Sensor
Shunt
Zero Sequence CT
Indicator lamp
Transformer
Others
Overvoltage And Undervoltage Protector Digital Meter Insulator Inverter Controller Voltage Stabilizer Meter Socket Smart Circuit Breaker
Case
Case Example
Download
About Us
Contact Us
Contact Us
News
Company News
Industry News
Technical Standard
Feedback

Protective current transformer classes for transient performance

Views : 1222
Update time : 2024-09-11 14:21:56
NOTE A larger variety of curves is given in the Technical Report IEC 61869-100 TR.  



2B.1.3 C-O-C-O duty cycles 

The transient dimensioning for auto-reclosure duty cycles has to be done separately for each cycle according to the equations given above. 

For cores having a high secondary time constant (typically TPX cores), there is no significant flux declination after t’. 

For cores having a low secondary time constant (typically TPY and TPZ cores), the secondary linked flux declines exponentially with the secondary time constant  Ts during the fault repetition time. In this case, no analytical formula exists for the time argument t in the term for the first cycle, and several case differentiations may be necessary.  

Fig. 2B.7 shows a typical case where saturation is reached after  t’al. The flux is limited to saturation flux before  t’ is reached. It declines to a value which is low enough to remain below saturation up to  t’’al. Ignoring saturation (shoved by curve, the declined flux starts from a higher level at the beginning of the second cycle. This example demonstrates the interdependency between the core dimensioning in the first and in the second cycle, and the determination of Ktd. 

NOTE 1 The formula for the C-O-C-O-cycle, which was given in the preceding standard IEC 60044-6, ignores saturation within the first cycle and leads in many cases to unnecessarily high Ktd values. See Fig. 2B.7. 

It is therefore recommended to draw a graph similar to the one in Fig. 2B.7, in order to make oneself familiar with the actual situation.
Previous :
Next :
Related News
Read More >>
Where Is the HK-58 Current Transformer Used in Malaysian LV Projects? Where Is the HK-58 Current Transformer Used in Malaysian LV Projects?
Sep .28.2026
HK-58 current transformer is designed for Malaysian LV switchboards, busbar panels and energy monitoring upgrades, enabling easier current measurement in factories and commercial buildings without major wiring changes.
Together Under the Same Moon: Celebrating Mid-Autumn Festival with Our Team Together Under the Same Moon: Celebrating Mid-Autumn Festival with Our Team
Sep .24.2026
HEYI celebrates the Mid-Autumn Festival by preparing thoughtful gifts for employees, expressing appreciation for their dedication, teamwork, and contribution while highlighting a warm and people-centered company culture.
Where Is the LMK5-100 Current Transformer Used in Australian Electrical Projects? Where Is the LMK5-100 Current Transformer Used in Australian Electrical Projects?
Sep .18.2026
Explore where the LMK5-100 current transformer is used in Australian switchboards, energy meters, busbar systems, factories, solar projects and infrastructure for accurate high-current energy monitoring.
Where Is a Current Transformer Used in South Africa’s LV Electrical Projects? Where Is a Current Transformer Used in South Africa’s LV Electrical Projects?
Sep .14.2026
Discover where a current transformer can be used in South Africa’s LV projects. Learn how DP-23 supports electrical panels, energy meters, motors, HVAC, and LV busbars with split-core installation, flexible ratios, and easy retrofit.