ABB 15.04.2005 Instrument Transformer

standard

Compliant with IEC 61869 standard, it can also be produced according to GOST, IEEE and other standards. Please consult the sales representative.

voltage transformer

Basic functions and principles

Function: Provide a secondary voltage proportional to the primary voltage for the secondary circuit, typically 100V, 110V, or 120V.

Principle: Through electromagnetic induction, the conversion ratio K=U ₚₑ/U ₛᵣ=N ₁/N ₂, where U ₚₑ is the primary voltage, U ₛᵣ is the secondary voltage, and N ₁ and N ₂ are the number of turns in the primary and secondary windings, respectively. The number of turns in the primary winding is greater than that in the secondary winding.

Key parameter

Rated primary voltage (U ₚₜ)

From the perspective of connection, it is divided into phase to phase voltage and phase to ground voltage, such as phase to phase voltage of 10000//100V, phase to ground voltage of 10000/√ 3///100/√ 3, 100/3V. The commonly used values specified by IEC include 3.3, 6.6kV, etc.

Rated secondary voltage: Any ratio can be produced, but the standard secondary voltage is preferred to be 100, 110, or 120V. When single-phase transformers are connected to ground, the rated secondary voltage for star connections needs to be divided by √ 3, and for open delta connections it needs to be divided by 3. Mixed ratio voltage transformers can also be produced.

Rated voltage factor: used to determine the maximum voltage that the transformer must meet the relevant thermal and accuracy requirements within a specified time. The ABB single pole voltage transformer is designed to be 1.9 × U ₚᵣ/8h, and the double pole is 1.2 × U/continuous. Different voltage factors can be discussed with the sales representative.

Number of windings and reconnection

Up to three secondary windings can be produced for measurement, protection, or ground fault indication, and can also be reconnected, such as a single pole insulated transformer with two secondary tap windings, one of which is the remaining winding.

Accuracy level: There are measurement categories of 0.2, 0.5, 1, and 3, and protection (a-n) and/or residual (da dn) categories of 3P and 6P. The measurement category is between 80% and 120% of the rated voltage at rated frequency, with voltage error not exceeding the IEC specified value. The protection category is within the range of 5% of the rated primary voltage to the rated voltage factor multiplied by the rated primary voltage (such as 190% when 1.9 times the rated primary voltage), with voltage ratio error not exceeding 3% (3P category) or 6% (6P category).

Fuse: In the supply of fuses for single pole voltage transformers, there are different specifications for the rated current, voltage, and whether the fuse has a firing pin.

Terminal markings

According to IEC standards, single pole primary winding A-N, secondary winding a-n (star), da dn (open triangle); Bipolar primary winding A-B, secondary winding a-b.

Thermal output: Under star connection and rated primary voltage U ₚᵣ, the maximum power that the transformer can achieve with a ratio error of ± 10%. Different voltage levels have different thermal output values, such as 12-17.5kV (TJC 4&TJC 5) and 400VA.

Other features

Parameters such as frequency, insulation level, ambient temperature, standard, cable loss, and load are the same as those of current transformers.

Example

Purchase order example: Current transformer TPU 40.13, 50//5/5 A, EXT 120%, 15/15 VA, 0.5FS5/5P10 grade, I ₜₕ=40kA/s, I dyn=100kA，12/28/75 kV，50Hz，IEC 61869 - 2， Environmental temperature 40 ° C, polarity P1-P2, with capacitive voltage divider.