The Power Quality Meter that brings the Smart Grid within reach.
Capabilities that formerly required separate, expensive, specialized equipment and consultants – now available in a compact, affordable device.
ANSI /IEEE Standard C37.2 – Standard for Electrical Power System Device Acronyms describing the OTELLO multi-function metering device
OTELLO records IEC 6100-4-30 Class A Edition 3 (2015) Power Quality standardized measurements of:
Meeting or exceeding the Class A requirements, plays an important role in providing accurate, reliable and comparable data. Access to this data facilitates accurate analysis and troubleshooting of power quality issues. Instruments lacking Class A compliance produce results that cannot be easily compared against each other. Class A compliant power quality metering instruments produce consistent data, giving technicians the confidence to accurately analyze complex power quality issues.
For both utility companies and large-scale, industrial energy users, it is critical to verify the quality of power and the source of non-compliance. Determining and solving the origination of power quality issues leads to a reduction of down-time, (lower cost) efficient energy use, fewer equipment failures and regulator compliance.
OTELLO is a comprehensive multi-function, single phase, dual-phase (split-phase), three-phase and Direct Current (DC) IEC 61000-4-30 Class-A Edition 3 (2015) Power Quality recorder with GPS-locked time synchronization.
The IEC 61000-4-30 Class-A standard defines the measurement methods, time aggregation, accuracy and evaluation, for each power quality parameter to obtain reliable, repeatable and comparable results. The standards are applicable in single-, dual- (split phase) and 3-phase AC power supply systems at 50 Hz or 60 Hz.
Additionally, the OTELLO instrument incorporates the IEC 62586-2:2017 definitions of the minimum set of parameters that must be implemented for Power Quality Instruments used in both portable and fixed installations. IEC 62586-2:2017 specifies functional tests and uncertainty requirements for instruments whose functions include measuring, recording, and monitoring power quality parameters in power supply systems, and whose measuring methods (class A or class S) are defined in IEC 61000-4-30.
It is a single feeder instrument with:
Number of channels: 4 x differential (3/4 Wire + 4th Diff)
Measurement input range: 0-600VAC ±850VDC
Input impedance: > 1MΩ
Number of channels: 4 x galvanically isolated
Measurement input range: 0-6AAC ±8ADC
Max continuous current: 10ARMS
3 sec Overcurrent withstand: 50ARMS
VA burden @ 5ARMS: < 1VA
Galvanic isolation: 1kV
Number of channels: 4 x differential
Measurement input range: 0-1VAC ±1.5VDC
Input impedance: > 200kΩ
The question of sampling rates for Power Quality metering is an important one to consider.
Most power quality monitoring is reliably processed at sampling rates of 256 or 512 samples per cycle. However, fast transients can cause damage to sensitive equipment and malfunctions in manufacturing processes. Lower-end power quality meters cannot reliably detect these fast transients as they only sample dozens of times per cycle. A fast transient power problem can do damage in a few millionths of a second. In order to capture these transients, sampling rates in the order of millionth of a second would be required.
The European standard for Electrical Fast Transient (EFT) testing is EN-61000-4-4. The U.S. equivalent is IEEE C37.90. Both of these standards are similar.
Identifying very fast transients requires the use of specialized, portable monitoring equipment that costs up to $20,000—and frequently requires an outside consultant (plus travel & subsistence). Newer ‘next-gen’ power quality meters boast sampling rates up to 6MHz. But is this practical considering the fact that these fast transients can only be measured directly – typically on 400v networks?
With fixed installations, the bandwidth of Voltage Transformers (VT’s) and Current Transformers (CT’s) is way too low to correctly pass through fast transients. Unless broadband VT’s and CT’s are used, what is the use of a 6 MHz sampling rate, if the VT & CT only accurately passes through 2kHz data?
The other challenge with such high resolution data in fixed installations, is where does one store it – pushing that much data over a digital network is very resource intensive and costly.
The practical application for such high measurement frequencies is therefore very limited.
However; the way this functionality has been implemented on the OTELLO platform, the user can clearly identify the root cause of fast transients. The OTELLO device captures enough data to identify whether a fast transient originated from a switching event or from lightning. One can even detect whether it was a direct lightning strike or an indirect one (induced). This solves the high sampling rate question, as the primary goal of monitoring fast transients is the identification of the source.
Compliance with IEC 61000-4-30 Class-A, dips, swells and interruptions must be measured on a full cycle and updated every half cycle, enabling the instrument to combine the high resolution of half-cycle sampled data points with the accuracy of full-cycle RMS calculations.
Aggregation windows are when a power quality instrument compresses measured data at specified periods. A Class-A instrument must provide data in the following aggregation windows:
OTELLO samples at 500 kHz on primary input signals. 50 kHz data is digitally retained and subjected to the IEC 61000-4-30 ED3.0 Class-A signal processing requirements.
Number of channels: 4 x galvanically isolated
Max voltage input: 300VDC
Number of channels: 4 x galvanically isolated
Max voltage input: 300VAC, 100mAAC
Overall accuracy: 0.1% on reading (10%-100%)
Power frequency measurement range : DC, 40-60Hz, 50-70Hz
Harmonic & interharmonic bandwidth: 1-64th, 2-9kHz
Synchronised data sampling rate: 500kHz
Fast transient capturing: >20μs
ADC Resolution: 16-bit
External time synchronization is required to achieve accurate timestamps, enabling accurate correlation of data between different instruments. IEC 61000-4-30 ED3.0 Class-A accuracy is specified with ± 20 ms for 50 Hz and ± 16.7 ms for 60 Hz instruments, regardless of the total time interval. The OTELLO multi-function metering device provides permanent ~100ns accurate to absolute-time clock-synchronisation using the built-in GPS. This provides industry leading accuracy when troubleshooting power quality issues and analysing grid wide data.
GPS clock sync accuracy: ±100ηs (from absolute time)
PTP clock sync accuracy: ±1μs (from absolute time)
NTP clock accuracy: ±1ms (from absolute time)
Built-in clock accuracy: ±1ppm (32 sec per annum)
The device also support open sFTP and REST server based protocols enabling them to be placed under control of other 3rd party software systems. OTELLO supports data imported from 3rd party devices using open formats like PQDIF, Comtrade and CSV files.
Security: Permanent 128-bit, end-to-end encryption
Ethernet: 2 x Gigabit ports
WiFi: 802.11 a/b/g/n/ac (Hotspot or Client)
Cellular (Optional): Sierra Wireless HL series
PTP support: IEEE1588
POE Plus support: IEEE802.3at (30W)(48V)
8GB on-board storage providing data storage of all IEC 61000-4-30 voltage and current 10-minute values up to the 64th harmonic
User-configurable triggering between different instruments: the patented XrossTrigger® feature
Power consumption (max): < 20VA
Supply voltage: PoE and/or 90-300VAC, 100-300VDC power factor corrected power supply
Supply frequency: DC, 42-69Hz
On-board battery: LiFePO4 – 1/2 hour power failure ride-through
Charge/discharge cycles (min): 2,000
Electrical isolation class: 600V Class II
Dimensions: 250mm x 135mm x 65mm (L x W x H)
Mounting options: DIN rail & wall mount
USB2.0 expansion port (powered): High speed (480Mbit)
OTELLO USER GUIDE
For detailed information on OTELLO’s specs and capabilities, download the PDF now.
Talk to us about your Electricity management challenges.
Here’s what to expect …