Spirax Sarco RIM20, Инструкция по установке и обслуживанию, Страница: 42 / 132

IM-P198-05 MI Issue 2 42
3.24 Alarm output connections
One alarm output (Alarm 1) is included on the standard RIM20 flowmeter. 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 terminals 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 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 with a separate power supply
(Figure 37), the second using the flowmeter power supply (Figure 38)(dc powered units only)
and the third with 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 flowmeter 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 Section 4).