Spirax Sarco SP500 - External Power Supply Option Board

IM-P343-35 CTLS Issue 5
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SP500 Electropneumatic Smart Positioner
Fig. 11
Fig. 10
4.3 External power supply option board
The SP500 can host an option board for 24 V power supply.
It's a 4 wiring diagram: 2 wires for current loop and 2 wires for power supply through a 24 V external voltage.
This reduces dramatically the voltage drop on the current loop. The drop is 7 V when the unit is powered by
the loop (2 wires), it falls to 1 V when the 4 wires conguration is used.
This board can be useful when you have many instruments connected on the same current loop. The fact is
that in this case, the total voltage drop on the loop could be higher than the maximum voltage drop that the
controller (PLC) can handle.
Refer to Section 6, 'Electrical connections' for wirings.
An option board is optionally available and can be mounted in situ. In this case please refer to the mounting
instruction below:
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Open the positioner (Figure 10).
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Switch o󰀨 the power supply.
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Switch o󰀨 the air supply.
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Unscrew the board as shown in Figure 11.