RESIN CASTED INSTRUMENT TRANSFORMERS FOR HIGHEST SYSTEM VOLTAGE FROM 11KV UPTO 33 KV

Ring Type Current Transformer (CT)

Graphic2Modern materials and future oriented designs guarantee the advantages

of our epoxy resin instrument transformers, viz:

  • MAINTENANCE FREE.
  • SUITABLE FOR TROPICAL CLIMATE.
  • DRY TYPE INSULATION.
  • HIGH MECHANICAL & ELECTRICAL STRENGTH.
  • MOUNTING IN ANY DESIRED POSITION.
  • HIGH RESISTANCE TO ARCING & TEMPERATURE CHANGES.
  • WINDINGS HERMETICALLY SEALED & EFFECTIVELY PROTECTED
  • AGAINST MOISTURE & MECHANICAL DAMAGE.

CURRENT TRANSFORMERS:

Bus Bar Type Current Transformers (CT)

Graphic2-1Current transformers are available in six versions:

  • Wound Primary, Open core, from 25 to 2000 Amps.
  • Wound Primary, concealed Core from 25 to 2500 Amps. (Box Type)
  • Bar Primary from 25 to 5000 Amps.
  • Type “M” Series for Metering circuits (Single Wound).
  • Type “P” Series for Protection circuits (Single Wound).
  • Type “MP” Series for both Metering & Protection (Double Wound).

I.E.C. STANDARDS

Box Type Current Transformers (CT)

Graphic2-2Current Transformers conform to the following International Standards:.

I.E.C. 60044 – 1 & 60044 – 2
B.S.S. 3988
V.D.E. 0414
WAPDA Spec. P – 115 & DDS – 80 : 2007

 

TESTS:

All the routine tests specified in the above standards are performed on each Current Transformer.

SERVICE CONDITIONS:

The Current Transformers have been designed to operate in conditions of relative

humidity upon 100% max, ambient temperature of 50 Coand altitude above sea level

upon and beyond 1000 Meter

VOLTAGE CLASS:

The C.Ts have been designed for 12 KV class of insulation. The impulse level is 95 KV

and one minute withstand voltage of H.V. side is 34/2 KV as per I.E.C. Standards.

STANDARD VALUES OF RATED PRIMARY CURRENT:

The standard values of Rated Primary Current are 25, 50, 75, 100, 150, 200, 250, 300, 400, 600, 800,

1000 upto 2500Amps and their decimal multiples or fractions. The referred values are those underlined.

Our range of production goes upto 2500Amps. For a sizeable order C.Ts can be manufactured above

2500Amps. The rated secondary current is 5Amps, 1Amp, other secondary can also be manufactured on

demand.

TESTS:

The Standard Values of Rated Output are 5 – 7.5 – 10 – 15 – 20 and 30 VA. for WAPDA. The rated outputs are

10 VA for Metering C.Ts and 15 VA for Protection C.Ts. Metering 0.5 M 5 & Protection 5 P 10 & 5 P 20.

SHORT TIME CURRENT RATINGS:

According to WAPDA Specification the short time current rating for one second in K. Amps is:

Type of C.T Metering Protection Metering Protection
Thermal Rating 12.5 / 25 12.5 / 25 12.5 / 25
Dynamic Rating 2.5 * 12.5 2.5 * 25 2.5 * 25

 

ACCURACY CLASS:

In general, we make C.Ts for the following class:

Type Metering Protection Metering Protection
Acc – Class 0.5 1.0 0.5 1.0
Acc – Limit Factor 5P10 / 5P20 5P10 / 5P20
Inst. Security Factor < = 10 < 10