Sierra 240-VTP, 241-VTP instruction manual Pulse Output Connections

Series 24-HP Instruction Manual Chapter 2 Installation

Figure 2-18. Non-Isolated 4–20 mA Output Using Meter Input Power Supply

Figure 2-19. Isolated 4–20 mA Output using Meter Provided Power Supply

Pulse Output Connections

The pulse output is used for a remote counter. When the preset volume or mass (defined in the totalizer settings, see page 3-8) has passed the meter, the output provides a 50 millisecond square pulse.

The pulse output optical relay is a normally-open single-pole relay. The relay has a nominal 200 volt/160 ohm rating. This means that it 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.

There are three connection options for the pulse output–the first with a separate power supply (Figure 2-20), the second using the flow meter power supply (Figure 2-21)(DC powered units only), and the third using the internal 24 VDC power supply (Figure 2-22)(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 pulse 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 pulse load comes from the meter’s power supply). Use the third configuration if you have an AC powered unit only. In any case, the voltage of the pulse output is the same as the voltage supplied to the circuit.

IM-24-HP 2-21