4.1.3. Collected Data

For the synthetic subset, 26 different load configurations, divided into 16 load classes (Table 5), were used, as well as their combinations (2, 3, and 8 loads). "Load configurations" means that one load may have more than one power level and/or that more than one equipment of the same class was used (e.g., two appliances of class LED lamp).

Linear and non-linear loads, ranging in power from 4 W up to 1.5 kW. The loads are powered on at different angles of the mains cycle, as per Table 6. Different turn-on trigger angles affect the loads inrush current, resulting in distinct waveform acquired at each angle. Each acquisition is commanded by the control board and consists of 16 voltage/current waveforms at the specified angles. The number of individual and multiple-loads acquisitions are presented in Table 7, in a total of 104 acquisitions, corresponding to 1664 waveforms. The number of acquisitions for multiple loads were limited by the jig's maximum power (1 kW).


**Table 5.** Characteristics of the synthetic subset of the LIT-dataset.




The sequence of events (ON and OFF) for the single and multiple loads are presented in Figure 4.

**Figure 4.** Data collecting jig: single, two, three, and eight loads ON and OFF events.

#### 4.1.4. Accuracy of the Jig

The jig's hardware initially went through a calibration process, and then its accuracy was evaluated based on a comparison with laboratory-grade measurement equipment.

The calibration process consisted of collecting data from resistive loads that were measured with an HP bench multimeter with a 5-digit-resolution and a precision better than 0.1 %. Since the voltage and current waveforms are bipolar (positive and negative values) but the 12-bit measurements of the A/D converters from the MyRio are unipolar (0 to 4095), an offset value corresponding to inputs at zero must be determined; as well as the gain factor to convert a binary value produced by the ADC to a voltage or current value (in Volts or Amperes). This calibration process is performed before every acquisition on the Jig, and the calibration values (Ki, Kv, ZeroOffsetI, ZeroOffsetV) are reported in the file config\_processed available in every acquisition folder of the LIT-Dataset.

The determination of the jig's accuracy was performed by connecting an oscilloscope (Agilent Infiniium 54830D) and a current probe (Tektronix A6302) during the acquisitions. A total of 28 acquisitions with different loads were performed while data were simultaneously acquired by the Jig and by the scope. Data from both sources were stored as spreadsheets and imported into MATLAB for comparison. Over the 28 acquired voltage and current waveforms, the maximum error was 3.2 % with a mean value of 2.1 %. This value of accuracy was considered as acceptable for a NILM dataset. Most datasets do not provide an accuracy evaluation for comparison.

## *4.2. Simulated Subset*

The simulated subset consists of data collected from twenty-eight different simulated loads grouped into seven kinds of electrical models, each one containing up to four power variations. The loads, waveform generation, and simulated subset settings are detailed as follows.
