Series 24-HP Instruction Manual | Chapter 2 Installation |
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Alarm Output Connections
One alarm output (Alarm 1) is included on the standard Innova-Mass™ Flow 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 volt/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 termi- nals is 200 volts. 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 elec- tronics 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 with a separate power supply (Figure 2-23), the second using the flow meter power supply (Figure 2-24)(DC powered units only) and the third with the meter provided power supply (Figure 2-25)(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 3-7).
Figure 2-23. Isolated Alarm Output with External Power Supply
Figure 2-24. Non-Isolated Alarm Output Using Internal Power Supply
