Precise and traceable measurements are important across all areas of life to ensure the performance and reliability of the measurement results. CSIR-NPL measures electrical quantities that are accurate, reliable and traceable to the SI units.  The National standards are realized, established, maintained, upgraded and disseminated to support industry, govt. sector, research and academia. We maintain LF & HF Voltage, Current, Microwave Power and Phasor Measurement Unit (PMU) parameters of electrical metrology. To maintain the international traceability, a number of international & bilateral intercomparisons under the umbrella of BIPM and APMP have been carried out. At CSIR-NPL, PMU-CAL system traceable to its national standards carries out a comprehensive calibration of a PMU as per IEEE Standard IEC/IEEE 60255-118-1:2018. It plays a vital role in power distribution sector through the PMU calibration and measurement system.

CSIR-NPL provides apex level calibration services in LF & HF Voltage, LF Current, Microwave power and PMU parameters as per ISO/IEC 17025:2017 standard to the industry, strategic sectors, STQC labs & private organizations of the country by maintaining their respective primary standards. We are disseminating measurement traceability in the above-mentioned parameters along with the other derived parameters and their measurement capabilities. We have 24 registered CMC’s and participated in more than 13 BIPM/APMP key/Supplementary comparisons to establish mutual degree of equivalence with the corresponding standards of the leading NMIs having internationally recognized traceability.   

a. LF Voltage & Current

Banks of Multi-Junction thermal converters (MJTC) are used for assigning AC DC transfer difference to the primary standard (MJTC) at 2 Volt and 5mA with the best uncertainty of ±5ppm. Therefore, the thermal transfer standard or thermal converters are designed to cover voltage range of 1mV volts to 1000 volts in the frequency range 10 Hz to 1 MHz with an uncertainty of ± (7 to 1000) ppm and current range of 1mA to 20 A in the frequency range of 40 Hz to 10 kHz with an uncertainty of ± (10 to 92) ppm.

Fig.: a) Measurement Setup for Primary Standard b) Measurement setup of DUC under Calibration

b. HF Voltage

High frequency (HF) voltage primary standard at NPLI has been realized using a twin resistance coaxial power mount in the frequency range of 1 MHz to 1000 MHz. The rf/dc transfer difference has been assigned at the input reference plane of the primary standard. The overall uncertainty in assigning RF DC transfer difference has been estimated to be within ±0.50% in the frequency range up to 1 GHz. With the establishment of the RF voltage primary standard, one can calibrate and assign the RF DC transfer difference to the transfer standard thermal voltage converters. HF Voltage standard is used to calibrate the RF Voltage meters, high frequency thermal converters using the well-established technique.

Fig.: HF Voltage Setup

c. Microwave Power

Coaxial Microcalorimeter system in 2.4mm connector, established as the primary standard of Microwave Power in the frequency range of 1 MHz to 50 GHz is an absolute method based on thermocouple principle for the determination of effective efficiency to the thermocouple sensor. This section provides apex level calibration services in microwave power parameter to the industry & user organizations of the country. In order to meet the growing demand for calibration of microwave equipments in this era of continuously growing technology, CSIR-NPL disseminates the traceability of microwave power from 1MHz up to 50 GHz. The absolute value of the effective efficiency has been assigned to the microwave power standard from 1 MHz to 50 GHz using coaxial microcalorimeter and Vector network analyzer. The expanded uncertainty of microwave power primary standard at 50 GHz is ±1.9%.

Fig.: a) 2.4mm Coaxial Microcalorimeter b) Coaxial Thermocouple sensor

d. Phasor Measurement Unit Calibration System

Today’s smart grid relies on phasor measurement units (PMUs) to deliver real-time critical data on the voltage, current, frequency and phase mainly within the power grid. It is mandatory that PMUs must be calibrated from a traceable calibrator system to ensure its consistency, accuracy and reliability. The CSIR-NPL Phasor Measurement Unit Calibration System (PMU-CAL) is capable of providing perfect solutions for PMU users, manufacturers, electrical power utilities and organizations associated with electrical power transmission. The automated PMU-CAL system fully complies with the IEC/IEEE 60255-118-1:2018 standard. The compliance testing of Phasor Measurement Unit (PMU) from 50V to 150V and 1A to 5A at 50 Hz with a frame rate of 10, 25 and 50 frame/seconds has become possible with the establishment of PMU-CAL system serving the nation through power sector. The CSIR-NPL PMU calibration system has an uncertainty of ±0.005% to ±0.010%. We use PMU-CAL system to generate a wide variety of complex signals, including flicker, harmonics. This feature gives us flexibility to calibrate PMUs by different manufacturers.

Fig.: Phasor Measurement Unit Calibration System

1. Digital Multimeter for LF Voltage from 1 mV to 1000 V and LF Current 1 mA to 20 A.
2. Voltage & Current Calibrator for LF Voltage from 1 mV to 1000 V and LF Current 1mA to 20 A.
3. AC Reference Source
4. Transconductance Amplifier (AC Current Source) up to 20 A
5. Micropotentiometer (Low Voltage TVC) from 1 mV to 200 mV
6. Thermal Voltage Converter 1 mV to 1000V
7. Thermal Transfer Standard 2 mV to 1000 V
8. Current Shunt 1mA to 20A
9. Amplifier with Load cell, Dynamic Strain Meter 0-5 V and upto 100 kN
10. AC Measurement Std 1mV to 1000V
11. AC Measurement Std/+Current Shunt 1mA to 20A
12. Handheld CRO 10Hz to 1MHz
13. CRO/DSO/MSO 10Hz to 1MHz
14. Frequency Counter
15. Universal Counter
16. Selective Microvoltmeter, Level Meter Up to 1000 MHz
17. RF Millivoltmeter Up to 1000 MHz
18. Synthesizer Sweep Oscillator 1 MHz to 18 GHz
19. RF Power Meter with Sensor 1 MHz to 50 GHz
20. Coaxial Thermistor Mount, Power Mount 1 MHz to 18 GHz
21. RF Power Transfer Standard 1 MHz to 50 GHz
22. Phasor Measurement Unit Calibrator System
23. Phasor Measurement Unit- P Class/ M Class Testing/Calibration as per IEEE

1. Dr. Saood Ahmad, Chief Scientist
2. Dr. Avni Khatkar, Scientist
3. Ms. Archana Sahu, Senior Technical Officer
4. Ms. Sunidhi Luthra, Technical Officer
5. Ms. Swati, Technical Officer

Dr. Saood Ahmad
Chief Scientist & Head
Section:  LF & HF Voltage, Current and Microwave Metrology Section

Division: Indian Standard Time
Email: ahmads@nplindia.org
Ph: +91-11-45608613 / 45609312 / 45609344

Fax: +91-11-4560 9310