ONICON F-2600 - Manual (Page 47)

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F-2600 & F-2700 Vortex Flow Meter Manual 02/15 - 0808-7 / 19204 Page 47
2.7.5 Alarm Output Connections
One alarm output (Alarm 1) is included on the standard meter. Two or more alarms (Alarm
2 and Alarm 3) are included on the optional communication board. The alarm output
optical relays are normally open single-pole relays. The relays have a nominal 200 V /
160 ohm rating. This means that each relay has a nominal on-resistance of 160 ohms and
the largest voltage that it can withstand across the output terminals is 200 V. However,
there are current and power specifications that must be observed. The relay can conduct
a current up to 40 mA and can dissipate up to 320 mW. The relay output is isolated from
the meter electronics and power supply. When the alarm relay is closed, the current draw
will be constant. Make sure to size Rload appropriately.
There are three connection options for the alarm output. The first has separate power
supply (Figure 37). The second uses the flow meter power supply (Figure 38) (DC powered
units only) and the third uses the meter provided power supply (Figure 39)(AC powered
units only). Use the first option with a separate power supply (5 to 36 VDC) if a specific
voltage is needed for the alarm output. Use the second configuration if the voltage at the
flow meter power supply is an acceptable driver voltage for the load connected. (Take into
account that the current used by the alarm load comes from the meter’s power supply).
Use the third if you have an AC powered unit only. In any case, the voltage of the alarm
output is the same as the voltage supplied to the circuit.
The alarm output is used for transmitting high or low process conditions as defined in the
alarm settings (see page 61).
AC or DC powered meters
ALARM
ALARM
Figure 40 Isolated Alarm Output Using External Power Supply
DC units only
Figure 41. Non-Isolated Alarm Output Using Internal Power Supply
+ 24VDC Out
- 24VDC Out
AC units only
Meter provided
DC Power
Figure 42. Isolated Alarm Output Using Meter Provided Power Supply
Pulse voltage = +V
Select resistor so that current
through pulse ≤ 40 mA.
AC units only
Meter provided
DC power