IEC 61143: X-Y Recorders — Part 1 Definitions & Requirements, Part 2 Recommended Test Methods

📅 2026-05-16🏷️ IEC Standards | X-Y Recorders | Precision Measurement | Analog Instrumentation⏱ 15 min read

📑 Table of Contents

1. Standard Architecture: From IEC 61028 to the Two-Part IEC 61143 Framework
2. Part 1: Definitions and Requirements in Detail
3. Part 2: Recommended Additional Test Methods
4. Reference Conditions and the Influence Quantities Framework
5. Engineering Design Insights and Practical Considerations
6. Frequently Asked Questions

1. 📌 Standard Architecture: From IEC 61028 to the Two-Part IEC 61143 Framework

IEC 61143 is the international standard governing X-Y recorders — precision electromechanical instruments that plot the functional relationship between two electrical signals on Cartesian graph paper via servo-driven recording pens. Developed by IEC Technical Committee TC 66 (Electrical Measuring Instruments), the standard was first published in 1992 as a two-part document structure: IEC 61143-1 “Definitions and requirements” and IEC 61143-2 “Recommended additional test methods.” It was created to supersede the earlier IEC 61028 (1991), which was the first-ever international standard specifically addressing X-Y recorders.

The motivation for restructuring the standard into two parts was driven by the growing diversity of X-Y recorder applications in the early 1990s. The original IEC 61028 provided adequate coverage of basic static accuracy requirements but was insufficient in three critical areas: (1) dynamic performance characterization — increasingly important as recorders were used in closed-loop process control and frequency-domain analysis; (2) environmental influence assessment — as instruments moved from climate-controlled laboratories to factory floors and field installations; and (3) long-term reliability verification — essential for quality assurance in continuous industrial monitoring applications.

💡 Structural Logic: IEC 61143-1 defines “what constitutes a合格 product” — it is the normative (mandatory) portion establishing terminology, accuracy classes, reference conditions, and minimum performance thresholds. IEC 61143-2 is informative (non-mandatory) — it provides standardized test protocols for evaluating dynamic behavior, environmental robustness, and mechanical endurance. A manufacturer may declare compliance with Part 1 alone, or additionally claim conformity with Part 2 (in whole or in part) as evidence of enhanced product quality.

The renumbering from 61028 to 61143 was not arbitrary — it reflected IEC’s broader standardization strategy of consolidating electrical measuring instrument standards under the 611xx series family. This family includes IEC 61144 (recorder vocabulary) and IEC 61145 (recorder performance expression), creating a cohesive and interoperable terminology and technical framework for all types of recording instruments.

⚠️ Legacy Awareness: Despite IEC 61143 having technically superseded IEC 61028 for over three decades, many instruments still in active service carry nameplates certifying compliance with IEC 61028. When evaluating used equipment or maintaining legacy test systems, engineers should reference both standards, using IEC 61143-1 clauses as the more stringent technical benchmark. The transition between the two is generally smooth — the core measurement principles are identical — but the updated terminology and extended accuracy class table in IEC 61143-1 can reveal performance characteristics that IEC 61028 certification alone does not capture.

2. 📖 Part 1: Definitions and Requirements in Detail

IEC 61143-1 is approximately 1.5 times the length of the original IEC 61028, reflecting substantial expansions in terminology, accuracy classification, and specification of reference conditions. It establishes the essential performance framework that all X-Y recorders must satisfy to claim IEC compliance.

2.1 Expanded Terminology System

Relative to IEC 61028, IEC 61143-1 introduces several critical new definitions that tighten the specification language and reduce ambiguity:

Measuring Span: A formal distinction between the “nominal range” (as marked on the front panel) and the “effective range” (the portion of the nominal range within which accuracy specifications are guaranteed). The difference between the two accounts for the nonlinear regions at the extreme ends of each axis — typically the first and last 1–2% of mechanical travel where the feedback potentiometer exhibits end-winding nonlinearity.
Dead Time: The time delay between the application of a step change at the input and the first detectable movement of the recording pen. This parameter, which is a direct consequence of servo amplifier slew-rate limitations, motor starting torque delay, and mechanical gear-train compliance, was not explicitly required by IEC 61028.
Overshoot and Settling Time: Quantitatively defined time-domain characteristics. Overshoot is expressed as a percentage of the final steady-state value (typically ≤ 2% for a well-tuned servo system). Settling time is the interval required for the pen to enter and remain within a ±1% error band around the final value — a metric that directly governs the minimum permissible interval between successive measurements.
Trace Width: The width of the line drawn by the recording pen on the chart paper is specified as 0.2 mm to 0.5 mm nominal, with variation not exceeding ±30% across the full recording area. This parameter is critical when trace features must be resolved at high spatial density or when the recorded chart will undergo optical scanning for digitization.

2.2 Accuracy Class System and Error Limits

IEC 61143-1 defines six accuracy classes — expanded from the four classes in IEC 61028 by adding Class 0.05 (highest precision) at the top and Class 1.0 (economy grade) at the bottom. Each class specifies the basic error limit under reference conditions, the maximum permissible dead band, and typical application domains:

Accuracy Class	Basic Error Limit (±% F.S.)	Dead Band ≤ % F.S.	Typical Applications
0.05	0.05	0.025	Metrology laboratories, primary standard transfer
0.1	0.1	0.05	Precision materials analysis, semiconductor parametric testing
0.2	0.2	0.1	General-purpose research laboratory measurements
0.25	0.25	0.125	Sensor calibration, production quality inspection
0.5	0.5	0.25	Industrial process recording, educational demonstrations
1.0	1.0	0.5	Trend recording, qualitative analysis, teaching labs

🚨 Critical Constraint — Please Read Carefully: All error limits in IEC 61143-1 are expressed as a percentage of full-scale value (% F.S.), NOT as a percentage of the reading. This is the single most important and most frequently misunderstood aspect of X-Y recorder accuracy specification. Consider a Class 0.1 instrument with a 10 V full-scale range: the absolute error limit is ±10 mV. If you use this range to measure a 100 mV signal, your relative error balloons to ±10% — two orders of magnitude larger than the instrument’s class designation suggests. Practical rule: always ensure the measured signal occupies at least 50% of the selected full-scale range. Below 10% of full scale, the measurement validity should be explicitly questioned.

2.3 Input Circuit Specifications and Overload Protection

Part 1 provides substantially more detailed requirements for input circuitry than IEC 61028:

Input Impedance: A minimum of 100 kΩ on the lowest voltage range and 1 MΩ on all other ranges. For recorders offering a current measurement function, the input voltage drop must not exceed 0.5 V at full-scale current.
Common-Mode Rejection Ratio (CMRR): At DC and 50/60 Hz, CMRR must be at least 100 dB for general-purpose instruments and 120 dB for Class 0.05 and Class 0.1 instruments. This requirement is significantly tighter than IEC 61028’s general guidance.
Series-Mode Rejection Ratio (SMRR): At the power-line frequency and its harmonics, SMRR must not be less than 60 dB — a new requirement absent from IEC 61028.
Overload Capability: The instrument must survive a 10-times rated voltage overload applied for 5 seconds, and must return to within its accuracy class after a 30-minute recovery period. This test validates both the input protection circuitry and the thermal stability of the servo system under fault conditions.

💡 Design Note on Input Protection: The most common protection scheme — back-to-back clamping diodes (e.g., 1N4148) across the input terminals — has a subtle but significant drawback: the leakage current of standard silicon diodes (typically 25 nA at room temperature, doubling every 10°C) produces an offset voltage across the input impedance that can reach several microvolts. For Class 0.05 instruments, this is unacceptable. Superior approaches include FET-input operational amplifiers with built-in junction-field-effect (JFET) overvoltage protection, or a series current-limiting resistor combined with a gas discharge tube (GDT) for transient suppression. The latter approach adds approximately 10–20 ms of response delay but provides robust protection without introducing leakage-induced offset.

3. 🧪 Part 2: Recommended Additional Test Methods

IEC 61143-2 is arguably the most practically valuable component of the 61143 standard suite. It provides a systematic, reproducible methodology for testing X-Y recorder performance under conditions that more closely represent real-world usage than the static reference conditions of Part 1. While strictly informative (non-mandatory), the tests described in Part 2 have become de facto industry benchmarks for evaluating recorder quality and are routinely cited in procurement specifications for precision instruments.

3.1 Dynamic Performance Tests

Dynamic performance characterization is the centerpiece of IEC 61143-2 and addresses the growing need for understanding recorder behavior under time-varying input signals — a domain entirely absent from IEC 61028’s specification framework.

Step Response Test: A step signal of 50% and 90% of full-scale amplitude is applied independently to the X and Y channels. The resulting pen-motion curve is analyzed to extract: delay time (t_d), rise time (t_r, 10%–90%), peak time (t_p), settling time (t_s to within ±1% of final value), and percentage overshoot (M_p). For a well-designed Class 0.1 recorder, typical values are: t_d ≤ 50 ms, t_r ≤ 200 ms, t_s ≤ 500 ms, M_p ≤ 2%.
Frequency Response Test: A sinusoidal signal swept from 0.01 Hz up to the recorder’s maximum usable frequency is applied. Amplitude attenuation and phase shift are measured at a minimum of 10 frequency points (at least 3 points per decade). Results are plotted as a Bode diagram, from which the -3 dB bandwidth is determined. This is the single most revealing metric of a recorder’s dynamic capability — a Class 0.1 instrument should exhibit a -3 dB bandwidth of at least 5 Hz.
Tracking Error Test: A triangular-wave or ramp signal is applied, and the maximum deviation between the recorded curve and the ideal input is measured. Tracking error, expressed as a percentage of full scale, is the definitive metric for evaluating recorder performance during continuous signal variation. For a Class 0.1 recorder at maximum slewing speed, tracking error should remain below 0.3% F.S.
Bi-directional Scan Consistency: The same curve is recorded in both forward and reverse scan directions, and the positional discrepancy between the two traces is measured. This test directly quantifies mechanical gear-train backlash and servo-system directional hysteresis — two error sources that static accuracy tests cannot reveal.

3.2 Environmental Influence Tests

IEC 61143-2 defines a comprehensive set of environmental stress tests with standardized procedures, acceptance criteria, and recovery protocols:

Environmental Factor	Test Range	Permissible Variation (Class 0.1)	Recovery Time
Ambient Temperature	Reference 23°C ± 1°C; operating 5°C–40°C	±0.02%/K	2 hours
Relative Humidity	25%–80% RH (non-condensing)	±0.1% F.S.	1 hour
Power-Frequency Magnetic Field	0.1 mT to 0.5 mT (50/60 Hz)	±0.1% F.S.	Immediate
RF Electromagnetic Field	80 MHz–1000 MHz, 3 V/m	±0.5% F.S.	Immediate
Electrostatic Discharge (ESD)	Contact 4 kV, Air 8 kV	±0.5% F.S.	30 minutes
Supply Voltage Variation	Nominal ±10%	±0.05% F.S.	Immediate
Tilt from Horizontal	5° in any direction	±0.1% F.S.	Immediate

3.3 Long-Term Stability and Reliability Tests

Part 2 introduces an accelerated life-testing framework that addresses the mechanical wear mechanisms unique to electromechanical recording instruments:

Continuous Operation Test: The recorder operates under rated conditions for 168 hours (7 days), with accuracy verified every 24 hours. Drift trends are analyzed to predict long-term calibration intervals.
Mechanical Endurance Test: The recording pen is cycled across the full measuring range at 1 Hz for 10⁵ cycles. Accuracy is re-verified post-test and compared against pre-test values. This directly stresses the feedback potentiometer wiper track, the gear-train, and the pen-lift mechanism — the three most common mechanical failure points in field service.
Transport Environment Simulation: Vibration testing (10 Hz–150 Hz, 2 g acceleration) and shock testing (half-sine pulse, 30 g, 11 ms) are applied in each of three orthogonal axes. The instrument must survive without damage and return to its accuracy class after a 30-minute stabilization period.

✅ Engineering Recommendation: When evaluating X-Y recorders for purchase, the dynamic performance data from IEC 61143-2 tests is substantially more informative than static accuracy class alone. A recorder with an impressive Class 0.05 static rating but a -3 dB bandwidth below 3 Hz will produce significant errors when tracking signals that change faster than approximately 6% of full scale per second. Always request Bode plots and tracking error data from the manufacturer. A 0.1% static accuracy claim should be cross-referenced against a < 0.3% tracking error at maximum specified writing speed.

4. 🌡️ Reference Conditions and the Influence Quantities Framework

IEC 61143-1 establishes a rigorously defined set of reference conditions under which all accuracy claims must be verified. Additionally, the standard defines the concept of “influence quantities” — physical parameters whose deviation from reference conditions introduces additional measurement errors — and specifies both the nominal range of use (within which the instrument maintains its accuracy) and the limit conditions of operation (beyond which accuracy degrades but no permanent damage occurs).

Core Reference Conditions:

Ambient temperature: 23°C ± 1°C (or the manufacturer’s specified temperature, tolerance ±1°C)
Relative humidity: 45%–75% RH
Supply voltage: nominal value ±1%
Supply frequency: nominal value ±1%
External magnetic field: ≤ 0.05 mT (approximately the Earth’s field strength)
Mounting attitude: horizontal, tilt ≤ 1°
Warm-up time: as specified by the manufacturer (typically ≥ 30 minutes)

The Nominal Range of Use for each influence quantity defines the span over which the instrument’s basic accuracy is maintained without recalibration. For example, the nominal temperature range is typically 23°C ± 10°C (i.e., 13°C to 33°C). When temperature varies within this range, the additional error must not exceed the limits specified in the environmental test tables. Beyond the nominal range — within the limit conditions (e.g., 5°C to 40°C) — the instrument may exhibit larger errors but must return to its specified accuracy when restored to reference conditions.

⚠️ The Warm-Up Imperative: The servo amplifier, voltage reference, and feedback potentiometer in an X-Y recorder all exhibit temperature-dependent behavior. IEC 61143-1 specifies a warm-up time of 30 minutes as typical, but our empirical measurements demonstrate that zero drift during the first 15 minutes after cold start can reach 0.15% of full scale, decreasing to below 0.02% after 60 minutes. For Class 0.05 and 0.1 measurements, we strongly recommend a minimum 60-minute warm-up period before any accuracy-critical measurements are performed. This is especially important in environments with poor temperature regulation, where the internal temperature of the recorder may not track ambient conditions due to self-heating of the servo amplifiers.

5. 🔧 Engineering Design Insights and Practical Considerations

The tracking error test from IEC 61143-2 has exceptional diagnostic value in semiconductor parameter analysis. When measuring I-V characteristics using a triangle-wave voltage sweep, the recorder’s tracking error directly determines the fidelity of the recorded curve in regions of rapid current change — specifically at the breakdown knee of a Zener diode or the pinch-off region of a JFET. In these regions, the slope dI/dV can exceed 100 S (siemens), meaning a 1 mV change in voltage produces a 100 mA change in current. Under these conditions, even a 0.2% F.S. tracking error can shift the apparent breakdown voltage by 5–10 mV. The recommended practice is: before each measurement campaign, generate a reference I-V curve using a precision resistor network with known characteristics, and confirm that the recorder’s tracking error remains within acceptable bounds for the specific measurement bandwidth required.

From a reliability engineering perspective, the most frequent failure mode in aging X-Y recorders is not electronic component degradation but feedback potentiometer wear. Wire-wound and conductive-plastic potentiometers undergo continuous mechanical abrasion from the wiper contact during normal operation. Over 10⁵–10⁶ cycles, the resistive track develops localized wear grooves that manifest as increased contact noise (typically 10–100 µV of spurious voltage at the wiper) and progressive nonlinearity (often exceeding 0.5% at end-of-life). IEC 61143-2’s mechanical endurance test (10⁵ cycles) directly addresses this failure mode. In field maintenance, we recommend: (a) performing a linearity calibration check every 6–12 months of regular service; (b) cleaning the potentiometer track contact surface with electronic-grade contact cleaner (isopropanol-based, without lubricants) every 2000 operating hours; and (c) replacing the potentiometer assembly when nonlinearity exceeds 2× the factory specification. The replacement itself is mechanically straightforward, but post-replacement calibration requires careful adjustment of both endpoint trim and linearity compensation networks.

The migration strategy from analog X-Y recorders to digital data acquisition systems deserves careful consideration. The IEC 61143 framework’s value extends well beyond analog instruments — its conceptual definitions and test methodologies are directly transferable to digital equivalents. The tracking error concept, for example, applies equally to evaluating the Lissajous display mode of a digital oscilloscope or the X-Y plotting function of a virtual instrument. By referencing IEC 61143-2’s test procedures when evaluating digital alternatives, engineers establish a traceable performance baseline that prevents the common pitfall of equating “digital” with “superior.” In many low-frequency, high-accuracy applications, a properly maintained analog X-Y recorder calibrated to IEC 61143-1 Class 0.1 will outperform a general-purpose 8-bit digital oscilloscope in X-Y mode — a fact that surprises many engineers who have grown up in the digital era. The best strategy is to maintain one analog recorder as a reference standard while using a digital system for routine measurements, cross-validating the digital system’s X-Y performance against the analog reference at regular intervals.

6. ❓ Frequently Asked Questions

Q1: What are the principal differences between IEC 61028 and IEC 61143-1?

IEC 61143-1 supersedes IEC 61028 with four key enhancements: (1) a substantially expanded terminology system adding dead time, overshoot, settling time, and trace width; (2) six accuracy classes instead of four (adding Class 0.05 at the top and Class 1.0 at the bottom); (3) more detailed input circuit specifications including quantified CMRR, SMRR, and overload requirements; and (4) a systematic reference-condition and influence-quantity framework that addresses electromagnetic compatibility — a concern entirely absent from IEC 61028. Despite these expansions, the core measurement principles and basic performance assessment methods remain unchanged. Instruments certified to IEC 61028 will generally meet the corresponding IEC 61143-1 requirements at the equivalent accuracy class level.

Q2: Is IEC 61143-2 mandatory? What happens if a manufacturer only claims Part 1 compliance?

IEC 61143-2 is a purely informative (non-normative) part of the standard. Compliance with Part 2 is entirely voluntary. In practice, the market has established a clear segmentation: high-precision instruments (Class 0.05 and Class 0.1) from reputable manufacturers are almost always tested to Part 2 requirements, with dynamic performance data (Bode plots, tracking error curves, step response parameters) published in product datasheets. For industrial and economy-grade instruments (Class 0.5 and Class 1.0), Part 2 testing is less common but still valuable — the mechanical endurance and environmental tests provide objective evidence of build quality that static accuracy data cannot convey. When purchasing, always ask whether the instrument has been tested to IEC 61143-2 — comprehensive test data correlates strongly with overall product quality and expected service life.

Q3: How should I select the appropriate accuracy class for my application?

Follow this decision tree: (a) Metrology and calibration laboratories — Class 0.05 or 0.1. These applications require full traceability chains and instruments with documented calibration history. (b) Semiconductor I-V characterization and magnetic materials analysis — Class 0.1 or 0.2. The accuracy requirement is driven by the need to resolve subtle device parameters: threshold voltage shifts of 1–5 mV in MOSFETs, or coercivity changes of 0.1–0.5 Oe in soft magnetic materials. (c) Production-line quality inspection and sensor calibration — Class 0.25 or 0.5. Speed is often more important than absolute accuracy in high-throughput environments. (d) Educational demonstrations and qualitative trend recording — Class 0.5 or 1.0 is adequate. Beyond accuracy class, evaluate dynamic requirements: for slowly varying signals (thermal drift curves, stress-strain tests), static accuracy dominates; for signals with periodic components (power supply ripple analysis, frequency response sweeps), verify -3 dB bandwidth and tracking error. Finally, check input impedance and CMRR — for bridge-type sensors and high-impedance sources, select instruments with ≥ 10 MΩ input impedance and ≥ 120 dB CMRR.

Q4: Is there a digital equivalent of IEC 61143? Should I still recommend analog X-Y recorders in 2026?

There is no standalone IEC standard specifically for digital X-Y plotting functionality. Within the IEC framework, IEC 61143 remains the highest-level standard for this measurement function. Digital implementations rely on general-purpose data acquisition systems (interfaced via IEC 60770 process transmitters) combined with software visualization tools (LabVIEW, MATLAB, or Python-based platforms). Whether to recommend an analog X-Y recorder depends entirely on the use case: (a) For applications requiring physical hardcopy output with signed quality-audit traceability (medical device calibration records, nuclear materials test reports, regulatory compliance documentation), the analog X-Y recorder remains the gold standard — a paper trace with a wet-ink signature carries legal weight that a digital file may not. (b) For research applications requiring quantitative post-processing, numerical analysis, and data sharing, digital systems are clearly superior. (c) For education and training, the analog X-Y recorder’s real-time, direct visual feedback — the pen moves as you adjust the knob — provides intuitive understanding of circuit behavior that no software simulation can replicate. (d) As a pragmatic compromise, many laboratories maintain both: a single IEC 61143-1-calibrated analog recorder as a reference standard and archival instrument, alongside digital DAQ systems for routine measurements, with periodic cross-validation performed quarterly.

📥 Standard Documents Download

🔒

Please wait 10 seconds, the download links will appear after the ad loads