Abstract
PMI manufactures a number of units that are designed specifically to monitor incoming power at the revenue meter base. This paper will focus specifically on the Guardian and iVS-2SX+ meter socket recorders and serve as a comparison of the form and function of both units.
Similarities
Forms
The iVS-2SX+ and the Guardian are both contained in a 2S meter socket housing. Both devices are self-enclosed and designed to fit behind existing residential revenue meters. The physical dimensions of both units are identical. Each measures 4.625″ x 6.75″ and weighs 3.6 lbs. Both units are designed to be used long-term in outdoor environments. Each can operate in environments with temperatures ranging from -20°F up to 135°F.
Functions
Both the Guardian and the iVS-2SX+ are designed for 200 Amp residential applications. Both are equipped standard with the ability to measure RMS voltage, RMS current, and apparent power. The Guardian and iVS-2SX+ both have the same recording accuracy specifications:
- Voltage: 0.33% of full scale
- Current: 1.0% of full scale
- Power: 1.0% of full scale
- Phase Angle: 1.0 degrees
- Power Factor: ± 0.02
- Displacement Power Factor: ± 0.02
Power Failure
Each unit can operate without any input voltage for up to 30 minutes, which allows both units to record down to 0 volts on all channels during power outages. Both models utilize less than 2.5 watts each.
Differences
Functions
In addition to RMS voltage and current available in the 2SX, Guardian comes equipped with the ability to measure and monitor power factor, demand, phase angle, real power, reactive power, displacement power factor, power usage, and harmonics to the 51st. The Guardian also measures IEEE/IEC Flicker. It has the same recording features as the Eagle 120, for easy inside/outside recording comparisons. The iVS-2SX+ also measures voltage and current. The ability to measure harmonics to the 31st and/or power factor are optional upgrades in the iVS-2SX+.
Sampling Rate
The Guardian measures up to 256 samples per cycle, and from 0 to 150 VAC. The sample rate of the iVS-2SX+ is 128 samples/cycle/channel for recordings from 0 to 140 VAC.
Communication
The Guardian is designed standard with high speed USB and Bluetooth, which allows for wireless downloads from the device. The iVS-2SX+ utilizes an RS-232 connection, and has no option for wireless connectivity.
Memory
The Guardian can hold 6.9 MB of Interval Graph recordings, 1000 records each of significant change and flicker recordings, and 1.7 MB of waveform capture recordings. It is also capable of advanced waveform capture recordings. The iVS-2SX+ holds 2.1 MB of Interval Graph recordings, 1000 records each of significant change and flicker, and 384 KB of waveform capture recordings. See Table 1 for a complete comparison of both devices.
Conclusion
While both the Guardian and iVS-2SX+ are reliable choices for monitoring incoming power at the revenue meter base, the Guardian has a number of standard features that the iVS-2SX+ does not such as wireless connectivity, increased memory and the standard capability to measure power factor, demand, phase angle, and harmonics to the 51st. The iVS-2SX+ can be a more economical choice particularly if features such as power, harmonics, and wireless communication are unnecessary.
| Specification | Guardian | iVS-2SX+ |
|---|---|---|
| Inputs | ||
| Channels | 2 channels | 2 channels |
| AC Voltage | 0 to 150 volts continuous per channel | 0 to 140 VAC RMS continuous |
| AC Current | 200 amps RMS | 200 amps RMS |
| Sample Rate | 256 samples/cycle/channel | 128 samples/cycle/channel |
| Measured Quantities per Cycle | ||
| RMS Voltage | Volts | Volts |
| RMS Current | Amps | Amps |
| Real Power | Watts | Watts (Optional) |
| Apparent Power | VAs | VAs |
| Reactive Power | VARs | VARs (Optional) |
| Phase Angle | Degrees | Degrees (Optional) |
| Power Factor | Watts/VA | Watts/VA (Optional) |
| Displacement PF | cos (phase angle) | cos (phase angle) (Optional) |
| Power Usage | kWh, kVARh, kVAh | kWh, kVARh, kVAh (Optional) |
| Harmonics | ||
| Voltage | to the 51st | to the 31st (Optional) |
| Current | to the 51st | to the 31st (Optional) |
| Measures | magnitude, phase, THD | magnitude, THD |
| Data Rate | 4,800 to 28,800 baud | — |
| Information Storage | ||
| Interval Graphs | 6.9 MB | 2.1 MB |
| Significant Change | 1000 records | 1000 records |
| Flicker | 1000 records | 1000 records |
| Waveform Capture | 1.7 MB | 384 KB (Optional) |
| Record Settings | ||
| Interval Graphs | 1 second to 4 hour interval user selected, stop-when-full, or wrap around memory modes | 1 second to 4 hour interval user selected, stop-when-full, or wrap around memory modes |
| Significant Change | 1V to 8V in 1V steps | 1V to 8V in 1V steps |
| Flicker Settings | User-defined, or conform to IEEE 1453/IEC 61000-4-15, and IEEE Std. 141 | User-defined, or conform to IEEE Std. 141 |
| Waveform Capture | Voltage and current threshold, periodic capture | (Optional) voltage and current threshold |
| Communications | ||
| Type | Bluetooth Wireless, USB | RS232 port |
| Power Supply | ||
| Power Consumption | Less than 2.5 watts | Less than 2.5 watts |
| Environmental | ||
| Operating Temp | -20°F to +135°F | -20°F to +135°F |
| Vibration | 10 Hz to 60 Hz, Amplitude 1.8 mm | 10 Hz to 60 Hz, Amplitude 1.8 mm |
| Shock | 60 Hz to 2kHz, Acceleration 25G | 60 Hz to 2kHz, Acceleration 25G |
| Power Fail Operation | Can operate without any input voltage for up to 30 minutes. This allows it to record down to 0 volts on all channels during power outages. | |
| Physical Dimension | ||
| Size | 4.625″ x 6.75″ | 4.625″ x 6.75″ |
| Weight | 3.6 lbs | 3.6 lbs |