Pods - PD2


Overview of the PD2

  • Monitors single phase power supply
  • Built in telephone line PSTN modem
  • Detects and reports all supply interruptions to electricity supply
  • Monitors key sites and supplies
  • Confirms restorations of supplies
  • Remotely programmable
  • Simple to install


Voltage Monitoring

The mains voltage is measured as full wave rectified RMS level with most of the ac component removed by a high pass filter. The signal is then peak limited, potted down to set the nominal voltage for 230 volts ac and high frequency filtered to remove unwanted noise. 4 voltage measurements are taken and averaged each half cycle of the mains. The result is used to determine the voltage status of the mains input every 20mS, or half mains cycle.

Operational Settings

The following settings are user set and may be reprogrammed locally using the diagnostic port or from the PC based Host Station during a routine call.

  • Nominal Voltage Level
  • Over Voltage Trip Threshold
  • Under Voltage Trip Threshold
  • Supply Fail Trip Threshold
  • Power Fail Period
  • Host Station Telephone No.
  • Test Call Frequency
  • Mains Connection

The PD2 is connected to the LV network via a fused plug fitted with a 3A fuse. This allows easy connection to the domestic electricity supply. The cable is fed through a rear panel mounted gland on the PD2 and soldered directly onto the POD PCB (connections are labelled L{ive}, N{eutral}, E{arth}). The input voltage to the LV approved transformer is fed through a 3A (quick blow) glass fuse and filtered by X-Y capacitors, to remove unwanted fast transients from the supply and prevent harmonics from being fed back into the supply.

Event Detection and Reporting

All events are date and time stamped locally within the PD2, the internal real-time clock is synchronised with the Host Station clock during every contact. Event Logs are stored in non-volatile memory (EEPROM). The following events are logged by the PD2:

  • Power Failure
  • Power Restored
  • Momentary Power Outage
  • Over Voltage
  • Under Voltage
  • Battery Low

All events are logged with the date and time of the event and up to 7 timers to describe the profile of the event. Most events produce immediate communication with the Host Station, however the PD2 can store up to 10 events prior to automatic download.


Event logs are communicated to the Host Station over a standard PSTN 2-wire extension line circuit. A V22 line modem is used to communicate with the PC based Host Station. Using the V22 standard ensures that the POD can exchange data with almost any proprietary modem installed throughout the world.

There are many spin-off benefits with this product, including monitoring supply to key customers dependent on electricity for medical care and essential processes.

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