⚡ Inductive current transformers (15–100 Hz) — additional requirements and tests: ratio error, phase displacement, composite error, instrument security factor FS, protective classes P, PR, PX, PXR, TPX, TPY, TPZ; PN-EN 61869-2

Electronics and EMC PN-EN 61869-2

Overview

WHAT THE STANDARD COVERS. IEC 61869-2:2012 (clause 1) applies to newly manufactured inductive current transformers for use with electrical measuring instruments and/or electrical protective devices, with rated frequencies from 15 Hz to 100 Hz. According to the foreword, Part 2 is used in conjunction with, and is based on, IEC 61869-1:2007 (general requirements), “however the reader is encouraged to use its most recent edition”; Part 2 follows the structure of Part 1 and supplements or modifies its clauses — a clause of Part 1 not mentioned in Part 2 applies as far as is reasonable; clauses, tables, figures and notes numbered from 201 are additional to Part 1, and additional annexes are lettered 2A, 2B, etc. The first edition of IEC 61869-2 (IEC technical committee TC 38 Instrument transformers) cancelled and replaced IEC 60044-1:1996 with Amendments 1 (2000) and 2 (2002) and IEC 60044-6:1992, and introduced a new approach to current transformers for transient performance; the theoretical background for dimensioning these transformers was moved to the report IEC 61869-100. The same series includes among others Part 3 (inductive voltage transformers), Part 4 (combined transformers) and Part 5 (capacitive voltage transformers).

TERMS (clause 3). Current transformer — an instrument transformer in which the secondary current, under normal conditions of use, is substantially proportional to the primary current and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. A measuring current transformer transmits an information signal to measuring instruments and meters, a protective one — to protective and control devices. Protective classes: P (without remanent flux limit, saturation behaviour specified for a symmetrical short circuit), PR (with remanent flux limit), PX (low-leakage reactance, without remanent flux limit — knowledge of the excitation characteristic, secondary winding resistance, secondary burden resistance and turns ratio is sufficient to assess its performance), PXR (as PX, with remanent flux limit; note of the standard: where low DC currents flow continuously, transformers with air gaps are used), TPX and TPY (transient performance; saturation behaviour specified by the peak value of the instantaneous error; TPY with remanent flux limit) and TPZ (with a specified secondary time constant; specified by the peak value of the alternating error component). Selectable-ratio current transformer — several ratios obtained by reconnecting primary winding sections and/or by taps on the secondary winding. Rated currents: primary Ipr, secondary Isr, short-time thermal Ith (the maximum primary current withstood for a specified short time with the secondary winding short-circuited), dynamic Idyn (the maximum peak value), continuous thermal Icth, primary short-circuit current Ipsc (r.m.s. value of the a.c. component of a transient primary short-circuit current on which the accuracy performance is based; usually smaller than Ith); exciting current Ie.

ACCURACY — DEFINITIONS (point 3.4). Ratio error in per cent: ε = (kr × Is − Ip) / Ip × 100 %, where kr — rated transformation ratio, Ip — actual primary current, Is — actual secondary current under the conditions of measurement; phase displacement Δφ — according to the definition of IEC 61869-1 (vector diagram in 2A.1). Rated resistive burden Rb; secondary winding resistance Rct — the actual secondary winding d.c. resistance in ohms corrected to 75 °C or another specified temperature (note of the standard: Rct is an actual value — not to be confused with the upper limit for Rct, which can be specified separately). Composite error εc — under steady-state conditions, the r.m.s. value of the difference between the instantaneous values of the primary current and of the secondary current multiplied by the rated transformation ratio, generally expressed as a percentage of the r.m.s. primary current. Rated instrument limit primary current IPL — the minimum primary current at which the composite error of the measuring current transformer is equal to or greater than 10 %, with the rated burden; instrument security factor FS = IPL / Ipr. Notes of the standard: the actual FS is affected by the burden — with a burden significantly lower than rated, larger currents will be produced on the secondary side in the case of a short circuit; the safety of the supplied apparatus is highest when FS is lowest. Secondary limiting e.m.f. of a measuring current transformer EFS = FS × Isr × √((Rct + Rb)² + Xb²) — according to the standard this method gives a higher value than the actual one, chosen in order to apply the same test method as for protective current transformers. Rated accuracy limit primary current and accuracy limit factor ALF (ratio of this current to Ipr); EALF = ALF × Isr × √((Rct + Rb)² + Xb²) for classes P and PR. Saturation flux Ψsat (the most suitable determination procedure — the d.c. saturation method of 2B.2.3; note: the former Ψs of IEC 60044-6 was a knee-point value, too low, and was replaced by Ψsat, which denotes complete saturation); remanent flux Ψr — remaining in the core 3 min after interruption of a magnetizing current producing Ψsat; remanence factor KR = Ψr/Ψsat in per cent; secondary loop time constant Ts = Ls/Rs; excitation characteristic — up to 1,1 times the knee point e.m.f.; knee point voltage — the voltage whose increase by 10 % increases the r.m.s. exciting current by 50 % (the knee point e.m.f. is defined in the same way and deemed equal to the voltage).

WHAT ELSE THE STANDARD CONTAINS (table of contents — only titles in the fragment we read). Clause 5: insulation levels (also inter-turn insulation requirements), rated outputs and rated resistive burdens, accuracy classes of measuring and protective current transformers, class assignments for selectable-ratio transformers, standard values of primary, secondary, continuous thermal and short-time currents. Tables 201–203: limits of ratio error and phase displacement of measuring current transformers of classes 0,1–1, 0,2S and 0,5S and limits of ratio error of classes 3 and 5; Tables 204–207: protective classes, error limits for P and PR and for TPX, TPY, TPZ and their specification methods; Table 208: terminal markings. Clause 6: temperature rise, terminal and rating plate markings. Clause 7 (Table 10 — list of tests): type tests — temperature rise, impulse voltage withstand on primary terminals, accuracy, short-time current tests; routine tests — power-frequency voltage withstand on primary terminals, accuracy, determination of Rct, determination of Ts, knee point e.m.f. Ek and exciting current at Ek, inter-turn overvoltage test; special tests — measurement of capacitance and dielectric dissipation factor, internal arc fault test; sample tests — determination of the remanence factor, determination of FS of measuring current transformers. Annexes: 2A (classes P and PR), 2B (transient classes), 2C (proof of low-leakage reactance type), 2D (determination of the thermal constant of oil-immersed transformers), 2E (alternative measurement of the ratio error), 2F (determination of the turns ratio error).

EDITION. IEC publication page (read on 06.11.2026): IEC 61869-2:2012, edition 1.0 of 2012-09-18, 140 pages, stability date 2027, “to be read in conjunction with IEC 61869-1:2007”; Interpretation Sheet 1 of January 2022 (IEC 61869-2:2012/ISH1:2022, 3 pages) has been included in this copy; work on a new edition at the stage “Approved for CD”.

STATUS (PKN card as of 06.11.2026). The card of PN-EN 61869-2:2013-06 (English version) has no withdrawal label: published 27-06-2013, 78 pages, Electrical Sector, KT 81 Instrument Transformers and Low-Power Transformers, “Adopts: EN 61869-2:2012 [IDT], IEC 61869-2:2012 [IDT]”, “Directive: 2014/35/EU”, “Replaces: PN-EN 60044-1:2000 - Polish version, PN-EN 60044-1:2000/A2:2004 - Polish version, PN-EN 60044-1:2000/A1:2003 - Polish version, PN-EN 60044-6:2000 - Polish version”, ICS 17.220.20. Polish title on the card: “Przekładniki -- Część 2: Wymagania szczegółowe dotyczące przekładników prądowych”. The “Scope” field (in Polish): “This part of IEC 61869 applies to newly manufactured inductive current transformers for use with electrical measuring instruments and/or electrical protective devices with a rated frequency from 15 Hz to 100 Hz”. Whether a Polish version of this edition exists — we did not check (the PKN search did not respond); whether the standard is in the list of standards harmonised with Directive 2014/35/EU — we did not check.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database of 02.11.2026; “Laboratories” tab on labcoda.pl, 06.11.2026). The number 61869-2 appears in 24 records at 6 Polish laboratories — 3 testing laboratories: AB 044 (1), AB 074 (5), AB 324 (12) — and 3 calibration laboratories: AP 166 (2), AP 168 (2), AP 182 (2). Forms: “PN-EN 61869-2:2013-06” (in 14 records of testing laboratories, usually with “IEC 61869-2:2012”, at AB 044 also with “EN 61869-2:2012”) and “PN-EN 61869-2:2013” without month (AB 324, 4 records for combined transformers); at the calibration laboratories — in-house procedures “based on PN-EN 61869-2:2013-06”: PP1 and PP3 (AP 166; PP3 also based on PN-EN 61869-3:2011), KMW-01 and KMW-02 (AP 168) and PW1 (AP 182). Standards cited in the same items: PN-EN 61869-1:2009 (AB 044, AB 074, AB 324) and PN-EN IEC 61869-1:2025-10 (AB 324), PN-EN 61869-3:2011, PN-EN 61869-4:2014-09, PN-EN 61869-5:2011, PN-EN 60060-1:2011 and -2:2011, PN-EN 60270:2003 (AB 324). We count the form “61869-2” not followed by a digit. Outside Poland there are 19 records at 5 Czech laboratories (1029, 1035, 1526, 1657, 1693 — “ČSN EN 61869-2” or “IEC 61869-2 ed. 1.0” with clause numbers, e.g. čl. 7.2.2, 7.3.1, 7.5.2). The “Laboratories” tab (“PN-EN 61869-2”, matching by family and number) shows 11 laboratories: these 6 Polish and 5 Czech ones, with the same number of items as the copy (query of the tab on labcoda.pl, 06.11.2026). We did not compare the current PCA scope documents of these laboratories with the copy.

WHAT THE LABORATORIES TEST (database copy, complete items). Testing laboratories: current transformers — electric strength of windings and temperature rise, IP degree of protection of the enclosure, corrosion resistance (AB 044, with PN-EN 61869-1:2009); current, voltage and combined transformers — mechanical strength, internal arc fault, temperature rise limits up to 4 kA, insulation withstand with lightning impulse voltage up to Up = 1200 kV, switching impulse up to Up = 900 kV and power frequency 50 Hz up to Ud = 300 kV, short-circuit withstand up to 100 kA r.m.s. / 250 kA peak (AB 074, five items); current, voltage and combined transformers with Un = (3,6–400) kV — ratio and phase error, radio interference voltage (RIV) and partial discharge (PD) level at Up up to 400 kV, withstand with lightning impulse voltage up to 4500 kV and switching impulse up to 2800 kV, power-frequency voltage 50 Hz up to 1000 kV; current and combined transformers up to 145 kV — short-circuit withstand up to 150 kA r.m.s. / 400 kA peak, temperature rise limits up to 20 kA, verification of the instrument security factor FS, current transformers also mechanical strength up to 5 kN and combined ones — short-circuit resistance (up to 145 kV) (AB 324, twelve items). Calibration laboratories (calibration, bridge method, in-house procedure): current and combined transformers — ratio of alternating currents at 50 Hz from 0,5 A to 5000 A to 5 A and to 1 A, CMC written as “0,03 %; 1,6 min”, outside permanent premises, for combined transformers also the voltage ratio from 0,44 kV to 110 kV (AP 166); from 5 A to 5000 A to 5 A and to 1 A at 50 Hz or 60 Hz, CMC “0,014 %; 1,3 min”, at permanent premises, combined transformers also voltages from 15 kV to 220/√3 kV (AP 168); from 0,5 A to 7500 A to 1 A and to 5 A at 50 Hz, CMC “0,025 %; 1,5 min” at permanent premises and “0,04 %; 2 min” outside them (AP 182).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Preparation: Part 2 does not work without Part 1 — the scopes combine PN-EN 61869-2:2013-06 with PN-EN 61869-1:2009 and with PN-EN IEC 61869-1:2025-10, while Part 2 follows the structure of IEC 61869-1:2007 and refers to its clauses; a report that does not give the edition of Part 1 does not say against which general requirements the test was made. Measurement: the actual instrument security factor FS is affected by the burden (Note 1 to 3.4.205) — a value determined with a burden other than rated is not the FS of the transformer; Rct is the actual winding resistance corrected to 75 °C (or another specified temperature) — an uncorrected value or one confused with the upper limit of Rct from the documentation gives false conformity; the saturation flux Ψsat must not be compared with the former Ψs of IEC 60044-6 (different definition — Note 2 to 3.4.210). Calculation: EFS and EALF are calculated quantities — FS or ALF and Isr are rated values, Rb and Xb — parts of the rated burden, and Rct — a measurement (routine test, point 7.3.201 — title); according to the standard the formula for EFS gives a higher value than the actual one. Ratio error ε and phase displacement are assessed against the class limits of Tables 201–203 (measuring) or 205–206 (protective) — these limits are not in the fragment we read. Calibration laboratories determine the current ratio (ratio error and phase displacement) using an in-house procedure “based on” the standard, with a stated CMC — this is calibration, not a type or routine test according to clause 7.

WHAT WE DO NOT GIVE. The fragment of IEC 61869-2:2012 we read (iTeh sample) covers the foreword, the table of contents and clauses 1–3 up to point 3.4.216 (knee point e.m.f.). We do not give the class error limits (Tables 201–207), the standard values (clause 5), the course of the tests (clause 7), Annexes 2A–2F or the content of Interpretation Sheet ISH1:2022, which we did not read. We did not read IEC 61869-1 and do not give its requirements or the differences between its 2007 and 2023 editions. We did not check the status of PN-EN 61869-1, -3, -4 and -5 on PKN cards. We did not check references to the standard in legislation.

Method principle

A current transformer is tested according to the general requirements of IEC 61869-1 as supplemented and modified by Part 2: type tests (temperature rise, impulse voltage withstand, accuracy, short-time currents), routine tests (power-frequency voltage withstand, accuracy, Rct, Ts, knee point e.m.f. and exciting current, inter-turn insulation test), special and sample tests (remanence factor, FS); accuracy is expressed by the ratio error ε = (kr·Is − Ip)/Ip × 100 %, phase displacement and composite error, compared with the class limits (IEC 61869-2:2012, clauses 3, 5, 7; course of tests and class limits — only titles in the fragment we read).

Applications

• Newly manufactured inductive measuring and protective current transformers, 15–100 Hz (IEC 61869-2:2012, clause 1)
• Protective classes P, PR, PX, PXR and current transformers for transient performance TPX, TPY, TPZ; selectable-ratio current transformers
• Together with IEC 61869-1 (general requirements), and for combined transformers — with IEC 61869-4
• In accreditation scopes: 3 testing laboratories (type and routine tests of transformers up to 400 kV) and 3 calibration laboratories (current ratio 0,5–7500 A)

Key parameters

Standard

Standard number

PN-EN 61869-2:2013-06 (English version; adopts EN 61869-2:2012 and IEC 61869-2:2012 [IDT])

Title (PL)

Przekładniki — Część 2: Wymagania szczegółowe dotyczące przekładników prądowych

Title (EN)

Instrument transformers — Part 2: Additional requirements for current transformers

Step-by-step procedure

1. Identification of the transformer and requirements

   Type (measuring, protective, selectable-ratio), class, rated currents and output, the edition of IEC 61869-1 used with Part 2 (foreword, clauses 3, 5).

2. Type tests

   Among others temperature rise, impulse voltage withstand on primary terminals, accuracy, short-time current tests (point 7.2 — titles).

3. Routine tests

   Power-frequency voltage withstand on primary terminals, accuracy, Rct (corrected to 75 °C), Ts, knee point e.m.f. and exciting current, inter-turn overvoltage test (point 7.3 — titles).

4. Special and sample tests

   Capacitance and dielectric dissipation factor, internal arc fault; remanence factor, FS of measuring current transformers (points 7.4–7.5 — titles).

5. Result

   ε, Δφ, εc, FS, ALF against the class limits (Tables 201–207 — titles), stating the edition of Part 1 and of Part 2. PN-EN 61869-2:2013-06 — current (PKN card as of 06.11.2026; English version).

Required equipment and apparatus

Health and safety (OHS)

• High-voltage tests (in the scopes up to 4500 kV impulse) and high short-circuit currents — segregated area, procedures for work on high-voltage equipment
• Internal arc fault test (point 7.4.6 — title) — hazard from the arc and rupture of the enclosure
• TECHNICAL NOTE: the actual FS is affected by the burden — with a burden lower than rated, larger currents flow on the secondary side in the case of a short circuit (Note 1 to 3.4.205)

Frequently asked questions