Outage Events; Frequency Events - ACR Electronics PowerWatch Reference Manual

Table of Contents

Events

Sag events

Impulse events

Outage events

Loss of Synchronization events

ACR Systems Inc.

Ó 2007,

5.2.1.6

Outage events

Outage Events

When PowerWatch records a sag of below 70Vrms for longer than a second it

displays the event as an outage. The VDR will go into self-powered mode

(battery) and will sample the voltage every eight seconds. As a result, the

shortest outage it will record will be eight seconds. When the power is

reapplied to PowerWatch, the VDR will not detect it immediately, but will wait

until the next eight-second sample before returning to the line powered

operational mode. This delay will prevent contact bounce being reported as an

event when PowerWatch is plugged into a standard electrical outlet.

Since PowerWatch's eight-second clock is not synchronized with outages, it

can sometimes report an outage as 16 seconds when in fact the outage only

lasted for slightly over one second. An example of when this would happen is

if a sag below 70Vrms occurred 6.9 seconds into an eight-second period. At

the 7.9-second point, PowerWatch would change to self powered mode and

report a minimum outage of eight seconds. If then, at the 8.1-second point,

power was restored, the VDR would not sample again until the 16-second

point.