Solutions For Instrument Transformer(CT&PT)

explore the important roles about  Instrument Transformer(CT&PT)

 

Instrument Transformers are of two types :

 

1. Current Transformer (or Series Transformer)

A current transformer(CT) is a device that is used to measure the current flowing through a conductor. It is used when the magnitude of AC currents exceeds the safe value of the current of measuring instruments, reducing/stepping down AC current from a higher value to a lower value for measurement/protection/control. The typical secondary current is 5 Arms.

 

2. Potential Transformer (or voltage Transformer)

voltage Transformer(PT) is a device that is used to measure high voltages in power systems accurately. It is designed to step down the high voltage levels to safer and measurable levels. The PTs transform high-voltage systems to low voltage, so they are compatible with meters, relays, and other measuring instruments used in power systems. are used where the voltage of an AC circuit exceeds 750 V as it is not possible to provide adequate insulation on measuring instruments for voltage more than this.

It is essential to test CT and PT to ensure the safety of the users and equipment. If these devices are faulty or not working correctly, they can pose a significant risk to those who use them or the equipment they are connected to. Testing these devices before installation will help to identify any defects or other problems and prevent them from causing significant harm.

To confirm the physical condition and electrical characteristics of the current transformer installed in the installation. Ensure the CT is connected to the system properly in all respects (primary and secondary).

 

 

Test items for the Current transformer test

Test items for voltage transformer test

1. CT Winding insulation Resistance test 2. CT Ratio test by primary injection:  a. CT Ratio,  b. Phase Angle Error 3. CT Winding Resistance Measurement 4. CT Loop Resistance Measurement 5. CT Polarity Test 6. CT Burden test 7. CT Magnetizing Current Test (Knee Voltage test) 8. Demagnetizing CT cores after all test 9. Inter Core coupling Test for bus differential test 10. High voltage test 11. Verifying secondary circuits, terminals, shorting/isolating links by primary injection 12. single point earthing check 13. phase identification

1. Winding insulation Resistance test 2. Voltage Ratio test by primary injection 3. Phase Angle Error 4. Winding Resistance Measurement 5. Polarity Test 6. Loop Resistance Measurement 7. Burden test 8. Phase Sequence test 9. Fuse Failure checks 10. Protective earthing 11. Back Energization Test at rated Voltage for 15 minutes

 

 

CT PT analyzer

In order to meet the test needs of users, and to ensure the maintenance and normal operation of CT PT, HUAYI developed the CT PT analyzer, which widely adopts customers’ advice and deep theoretical study. We provide different models with different working principles to satisfy the different test requirements.

 

Model:  HYCT-100

It adopts high-performance DSP and ARM, advanced manufacturing technology to ensure stable and reliable product performance, full-featured, high degree of automation, and high efficiency, in the domestic leading level, they are the professional testing equipment for transformer check in the power industry.

 

Major Technical Parameters: 

 

Usage		CT， PT
Output		0~180Vrms，12Arms，36A（peak value）
Voltage measurement accuracy		±0.1%
CT Ratio	Range	1~40000
	accuracy	±0.05%
PT Ratio	Range	1~40000
	accuracy	±0.5%
Phase	Range	±2min
	accuracy	0.5min
DC resistance	Range	0~300Ω
	accuracy	0.2%±2mΩ
Burden	Range	0~1000VA
	accuracy	0.2%±0.02VA
Power supply		AC220V±10%，50Hz
Environmental Conditions		Operating temperature : -10οC~50οC ，Humidity :≤90%
Weight and Dimensions		Dimensions: 365 mm×290 mm×153mm,Weight<10kg

 

 

Model HYFA series:

It is mainly used for field testing of P-class CT and PT. The test items mainly include excitation characteristic, transformation ratio, polarity, Degauss, 5％ and 10％ error curves, secondary circuit check, and withstand test of power frequency alternating current and secondary load. Adopt LCD, self-equipped mini type printer supporting field printing; supporting to use of USB flash disk to dump data, with simple and convenient operation.

 

 

Major Technical Parameters: 

Operational Power Supply:	AC220V±20V, 50～60Hz
Equipment Power Supply Output Waveform:	Sine Wave
Single Machine Output Voltage of Excitation Characteristic:	0～2500V
Excitation Current Set:	0～20 A
Single Machine Output Current of Transformation Ratio Test	0～1000 A
CT ratio measurement range	5～25000A/5A（5000A/1A）
PT ratio measurement range	1～500KV
Load Range	5～500VA
Resistance measurement range	0.1～300Ω
Error：	≤0.5%（0.3%*Reading+0.2%*Range）
Operating Temperature：	－10℃～+40℃
Relative Humidity：	＜90RH%
Altitude	≤1000m
Overall Dimension(Length×Width×Height):	450 *350 * 350（mm）
Weight:	≤28 Kg

 

 

 

IEC60044 GB1208 (-1) GB16847 (IEC60044-6)

IEC 60044-1: Instrument transformers – current transformer.

IEC 60694: common specifications for HV switchgear