Detailed behavior – Multi-Tech Systems 7500 User Manual
Page 298
Detailed Behavior
ION 7500 / ION 7600 User’s Guide
Page 298
Power Availability Technical Note
Detailed Behavior
The Availability framework measures Disturbance time from the Sag/Swell
module, Uptime from a counter module and meter Downtime from the
Diagnostics module. Meter Downtime is added to the Uptime count to provide the
total time of observation.
The meter uses three measurements when calculating the availability:
1.
Meter Uptime: the time the meter is powered and actively monitoring. The
time is measured by counting 1-second pulses from a periodic timer module.
2.
Meter Downtime: this time is measured by the meter’s internal clock and made
available through the diagnostics module. The diagnostics module downtime
register is updated on each power up. This calculation is accurate across a single
month boundary: any additional month boundaries are assumed to have 30
days. You must set the Sag limit above the minimum voltage level specific to the
power supply and wiring configuration of the meter (see “Sag/Swell Module
Configuration” on page 294 for specifications). If there is no control power then
it is assumed there is no power anywhere, and this time counts against
availability.
When the meter powers up, it takes about 15 seconds before the ION modules
are operational again. This power up time counts against the availability (a
single power up per year limits total availability to 6 nines). If the application
requires better resolution than this, then a UPS or other auxiliary power supply
for the meter should be considered.
If the meter or control power circuit is taken out of service for maintenance, you
can disable the measurement of meter downtime with ION software; see
“Pausing Availability” on page 297.
Number of Nines
ppm (% x 10,000)
Downtime (seconds/year)
Downtime per year
1
90%
3153600
36.5 days
2
99%
315360
3.7 days
3
99.9%
31536
8.8 hours
4
99.99%
3153.6
52.6 minutes
5
99.999%
315.36
5.3 minutes
6
99.9999%
31.536
31.5 seconds
7
99.99999%
3.153599998
3.2 seconds
8
99.999999%
.3153599998
.32 seconds
9
99.9999999%
.03153599998
.032 seconds
10
99.99999999%
.003153599998
.0032 seconds