S+S Regeltechnik HYGRASGARD KFF Operating Instructions, Mounting & Installation page 15

SUPPLY VOLTAGE:
For operating voltage reverse polarity protection, a one-way rectifier or
reverse polarity protection diode is integrated in this device variant.
This internal one-way rectifier also allows operating 0 – 10 V devices on
AC supply voltage.
The output signal is to be tapped by a measuring instrument. Output
voltage is measured her against zero potential (O V) of the input voltage!
When this device is operated on DC supply voltage, the operating volt-
age input UB+ is to be used for 15...36 V DC supply and UB – or GND for
ground wire!
When several devices are supplied by one 24 V AC voltage supply, it is
to be ensured that all "positive" operating voltage input terminals (+) of
the field devices are connected with each other and all "negative" opera-
ting voltage input terminals (–) (= reference potential) are connected
together (in-phase connection of field devices). All outputs of field de-
vices must be referenced to the same potential!
In case of reversed polarity at one field device, a supply voltage short-
circuit would be caused by that device. The consequential short-circuit
current flowing through this field device may cause damage to it.
Therefore, pay attention to correct wiring!
NOTE
For 4 ... 20 mA devices, DC voltage must be used (without residual ripple,
see permissible range of load resistance diagram). Do not use pulsating
DC voltage.
Connecting scheme
Power supply
AC 24V~ 0V
DC 15-36V = GND
Connecting scheme
Power supply
AC 24V~ 0V
DC 15-36V = GND
Load resistance diagram
800
700
600
500
400
300
250
200
50
10 15
Operating voltage (V DC)
Individual operation
Circuitry
V
Parallel operation
Circuitry Circuitry
Load resistance diagram
4 ... 20 mA
Admissible
range
20 25 30 35 36 40