3300 ACM Installation and Operation Manual Power Measurement Ltd.
2-16 Installation
2.7 KWH PULSE OUTPUT
The RS-485 communications port of the 3300 ACM can
alternatively be used to provide a kWh pulse output, suitable
for driving a relay. Figure 2.7.1 illustrates the connections
required. Pulses can be configured as KYZ or set to user-
selectable pulse width (10 to 990 ms). The maximum pulse
rate possible is 1 pulse per second. Section 3.8 describes the
programming and operation of this function in more detail.
CAUTIONS
1. Use only a Power Measurement ap-
proved external relay with the 3300
ACM. Using a non-approved relay
can seriously damage the RS-485 port
output and will void the 3300 ACM
warranty. Contact Power Measure-
ment for complete information regard-
ing relay specifications and applica-
tions.
2. The RS-485 port of any 3300 ACM
which is being used for kWh pulsing
must not be connected to any local
RS-485 communications network.
Doing so will inhibit all communica-
tions on the network.
2.8 MAINTENANCE
The 3300 ACM contains a non-volatile memory (NVRAM)
that provides an integrated battery backup system. The
rated life of the NVRAM battery is seventy years at 50
o
C
(122
o
F), 28 years at 60
o
C (140
o
F), and 11 years at 70
o
C
(158
o
F).
If the unit operates at less than 50
o
C for 60% of the time,
less than 60
o
C for 90% of the time, and less than 70
o
C for
100% of the time, the expected life of the NVRAM battery is
35 years. If the meter is operating in an environment where
the temperatures regularly exceed 60
o
C, the NVRAM should
be replaced every ten years.
Contact Power Measurement or your local representative for
information on NVRAM replacement.
NOTE
When the NVRAM is replaced, min/max
data (if equipped) may be lost. It is rec-
ommended that critical data be uploaded
via communications to a computer prior
to servicing. Setup parameters and cali-
bration of the unit will not be affected.
Other than NVRAM replacement, the 3300 ACM does not
require any regular maintenance.
-+
Control
Contacts
External Relay
To input of pulse
counter
(e.g. PML's 3750
PDC Power
Demand
Controller)
+
-
Figure 2.7.1 kWh Pulse Output
Connections
Courtesy of NationalSwitchgear.com
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