Current Sequencing - DPS Telecom NetGuardian 216 DCP User Manual

26

5.10.1 Current Sequencing

The thresholds for your analogs must be set from Under to Over in either ascending or descending potential (or
current) order. Thus, the settings of -46, -47, -53, and -54 corresponding respectively to major under, minor under,
minor over and major over is valid.
The analog alarms are set to measure voltage by default, and the thresholds are reported as actual units. To change
any one analog alarm to measure current, a circuit board jumper setting must be changed. Refer to section 4.7.2.1
(Jumper Options) for details on jumper locations and positions.
The analog threshold alarms can be entered in either ascending or descending order. This allows a low negative
voltage to be provisioned as either an under or over alarm to match the application context. In either case, the
analog value between the minor over and minor under returns an alarm clear condition.
Voltage
0
– 43 1
– 45
– 58
– 60
Point
1
2
3
4
5
6
7
8
9
MnU
Minor Under Minor Over
Fig. 5.19. Illustration of analog voltage/current changes to threshold alarm
Note: The descending configuration is useful for monitoring battery voltage. In the descending configuration, a 0
volt reading will alarm as a major under (MjU).
The jumper inserts a 250 ohm shunt resistor across the input to convert the sensors current output to volts. Use
ohms law to find the voltage drop across the 250 ohm shunt resistor (multiply the current by the 250 ohms
resistance). Please refer to the operation manual for your sensor to determine any other conversion factors. This
will allow you to correctly set the thresholds for over and under conditions.
2
3 6
4 5
Time
Ascending
MnO – A
MnO – C
MnU – A
MjU – A
MjU – C
MnU – C
MnO – A
MjO – A
MjO – C
MnO MjU
Major Under Major Over
8 9
7
Descending
MnU – A
MnU – C
MnO – A
MjO – A
MjO – C
MnO – C
MnU – A
MjU – A
MjU – C
Key
MjO A
Alarm
Ascending Descending
MjO MjU
MnO MnU
MnU MjO
MjU MjO
C
Clear