CMC 430: The lightest protection test set

The first multi-phase test equipment from OMICRON appeared in the form of the CMC 56. This device was significantly lighter than conventional test sets of the time, provided the necessary binary inputs and outputs, and above all, could be controlled with user-operated software on a PC without demanding any programming knowledge. Another feature was the high accuracy in amplitude, phase, frequency, and power, allowing the device to be used for calibration purposes, especially for measuring transducers and meters. The CMC 56 was the first test set of its kind to provide accurate DC and pulse measuring inputs of the same accuracy. Five years later, OMICRON presented the compact version, the CMC 156, which even then weighed just under 10 kg. The device was available until 2012 and is still in widespread use.

Newer protection and test sets have been fitted with Ethernet and other interfaces as standard for a long time. Various devices, such as the CMC 256-6, can be easily retrofitted with these, since the capability of test and analysis tools to be adapted to new requirements is essential for safeguarding the value of an investment. Upgrades for hardware and software/firmware over that period of dynamic technological development have allowed the service life of test sets to be extended to 10 – 15 years.

CMC 430 – a lot of innovation in a small space
The dynamics of the anticipated future developments is expected to take place more in the realm of software, so the time was ripe for presenting a new test set. There was ample potential for a raft of improvements and new features, and finally there was a gap to be filled in terms of mobility.
• Small and light: Deliberate efforts were made to reduce the weight appreciably to less than that of the CMC 156 model (9.8 kg). The result is a multi-phase secondary test set weighing a mere 8.7 kg – currently the lightest in the world.
• Extremely accurate: Accuracy regarding amplitude, phase, frequency, and the derived variables power (P, Q, S) and energy (Wh, varh) is essential when calibrating meters, measuring transducers, and other measuring instruments. The CMC 430 is more accurate than all previous CMC models, at least with a defined load range.
• Improved sturdiness and handling: The new in-house housing design, with reinforced corner and edge protection and all connections and control elements mounted at the front, puts a desire expressed by many customers into practice. The unit can be used vertically, sideways or in the classic horizontal position. The shock-absorbing rubber corner elements protect the sensitive electronics against mechanical influences, while the integrated handle replaces the typical swivel handle of the past.
• Output status signaling: LEDs show the status of the voltage and current booster outputs, and the AUX DC auxiliary voltage output. In addition, the user can activate an acoustic signal to indicate the “Outputs Active” and “Overload” status audibly as well as visually. The user is warned in advance of the impending output of a preset DC auxiliary voltage for 20 seconds both visually and audibly. These indicators give a better overview of the test progress.
• Six voltages: The CMC 430 is the first protection test set from OMICRON with two complete triple voltages (6 x 150 V), with all the outputs having the same “N”. This not only allows the neutral overvoltage from the open delta connection to be simulated as a 4th voltage, but also two complete voltage systems as well. Synchro-Check devices, synchronisers and integrated protection and control systems (for example, SEL 421) with six voltage inputs can therefore be tested without additional voltage amplifiers.
• Six further developed analog/binary inputs: Six measuring inputs insulated from each other (CAT II-600 V) with an additional 10 mV measuring range, improved measuring accuracy and higher sampling rates (10 and 40 kHz) are further features of the CMC 430. The sampling values of the analog channels are linked with the data from the binary channels (electrical or GOOSE) and up to two SV streams, and continuously sending to the control computer. Calculations and signal visualisation are carried out using the EnerLyzer Live software. The powerful, hybrid measurement functions (analog, binary, GOOSE, and SV) make carrying another instrument unnecessary, which also reduces costs.
• DC auxiliary voltage with high short-time output power: For test objects with high short-time inrush currents in the DC supply, the auxiliary voltage output provides a power of approximately 120 W for a period of about two seconds (permanently available figure is 50 W). This is enough to supply practically any protection device if the station supply is not available.
• Free choice of connection: The CMC 430 controller can be connected by wire using an Ethernet or USB cable or wirelessly over Wi-Fi, although a wireless connection requires a special mini USB Wi-Fi adapter.
• Measurements with the instrument: The CMC 430 is compatible with the known and legacy software packages from OMICRON. The Test Universe 3.20 software is used for parameter-based testing and calibrating. More complex tasks, such as testing distributed protection systems, are made considerably easier by simulation-based tests with RelaySimTest. The CMControl P app remains available for simple manual and semi-automatic tests, running either on a Windows notebook or an Android tablet.
• EnerLyzer Live measurement option: The EnerLyzer Live measuring tool enhances the CMC 430 by adding powerful hybrid measuring, evaluation, and recording functions. The software integrates the measurement data from the analog and binary inputs and the virtual inputs (GOOSEs) and up to two data streams (sampled values as per IEC 61850-9-2).

Authored article by:
Reinhard Kuntner
Product Manager
OMICRON