Delta OHM HD2817T Series, Manual

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11. Instruments fitted with relay outputs
The HD2817T...-DR models are fitted with three relays with ON/OFF or control and alarm
functions.
The RL1 and RL2 relays have a free potential exchange contact, the RL3 alarm relay has a free
potential normally open contact.
The three relays can be configured independently. You can associate one of the six available
physical quantities (temperature, relative humidity, absolute humidity, mixing ratio, dew point,
wet bulb temperature) to the RL1 and RL2 relays.
The RL3 relay is employed for the alarms.
To set the relays parameters, you can use the CONF. OUT >> Output Relay menu
item .
When the relays are de-energised, the state of the contacts is that reported in the silk screen
on the terminal board: it is the same when the instrument is not powered or in “off-line” mode.
Please account for this during configuration of the instrument.
In “suspend” mode the contacts are maintained in the same position in which they were when
the suspend mode occurred.
Relay idle, with instrument non
powered or in OFF-LINE mode
Contact
RL1
9 – 10 Closed contact
9 – 8 Open contact
RL2
6 – 7 Closed contact
5 – 6 Open contact
RL3 3 – 4 Open contact
To simplify the system maintenance operations or to check the correct configuration, the
relays can be blocked in the ON or OFF fixed position from the menu.
A special menu item (“ On Error ”) controls the behaviour of the RL1 and RL2 relays, if the
measurement associated to each one goes in error. The error can occur when the
measurement exceeds the functioning limits indicated in the technical information, and when
the probe becomes faulty or gets disconnected.
11.1. Working relays RL2 and RL2
The following parameters should be set per each working relay ( RL1 and RL2 ):
1) The quantity associated to the relay functioning (“ Mode” in the menu).
Per each relay you can select one of these items (between parenthesis the indication
shown on the display):
Relative Humidity ( RH Rel. )
Absolute Humidity ( AH Abs. )
Mixing Ratio ( MR Mix. )
Dew Point ( Td Dew. )
Temperature ( T Temp. )
Wet bulb temperature (Tw Wetb.)
(Force OFF) blocks the relay in a de-energised state ( For. OFF )
(Force ON) blocks the relay in an energised state ( For. ON )
The last two items are useful during system maintenance and instrument configuration.