2.7.1 Mains (line) supply
The hygrometer will operate on 90-264V AC, 50/60Hz mains (line) voltage. The power
consumption is 7.5VA.
An external fuse and a suitable switch or circuit breaker must protect the mains supply of the
hygrometer, which should be near the unit. Use a 1A antisurge Fuse.
13
14
L
N
Fuse 100-240Vac 50/60Hz - 1A antisurge
RECOMMENDED POWE R CONNECTION
If the relay outputs are to be used to carry mains (line) voltage, it is recommended that the
relay mains (line) supply should be switched and fused in a similar manner but should be
separate from the hygrometer mains (line) supply.
2.7.2 Sensor Connection
The sensor is connected to the hygrometer with the low impedance co-axial cable provided.
This low impedance cable may be up to 1 km long.
Note that the body of the sensor is not isolated. It is important that the earth potential at the
sensor is the same as that in the power supply earth to avoid stray pick-up. This is very rarely
a problem, but if in doubt, check for a voltage between the sensor body and the sensor holder
before installing the sensor.
2.7.3 Alarm Relay Outputs
The relay outputs of Alarm 1 and 2 are single pole double throw contacts rated at 2A resistive
at 120Vac or 240Vac, 50/60Hz.
The relay contacts are inherently isolated from the instrument and from each other.
2.7.4 Linear (Analogue re-transmission) Output
A 10-bit analogue signal representing the dewpoint is re-transmitted by the output, which is
factory preset to voltage or current output. The range of re-transmission can be set to
anywhere within the hygrometers’ operating range. See section 4 on how to set your options.
The output is isolated from the rest of the unit and should be wired using a twisted pair or
screened wire.
Load Impedance is 500Ω maximum in mA ranges and 500Ω minimum in voltage ranges.
2.7.5 Alarm Transistor Open Collector Outputs
The open collector outputs of Alarm 1 and 2 are NPN outputs. The return is common for both
collectors.
dewTEC DS2000 User’s Manual Page 7
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