ULM-nav-2.4
to terminal 1 and the negative pole (0 V) to terminal 2 – see fi gure 2 and 3. While making the connections the cable
must not be energised!
The level meter is connected to an evaluating device using a suitable two-core cable with an external diameter of
6-8 mm (recommended cross section of cores: 0,5 – 0,75 mm
2
). A shielded cable must only be used if the lead is
longer than 30 m or in the case of parallel lead togheter with power lines.
For supplying we advice a stabilized supply unit of safe voltage 12-30 VDC (SELV type), which can be part of the
connected evaluating device (for the ULM-55N type) or through an intrinsically-safe isolating repeater with supply
voltage 12-30 VDC, e.g. IRU-420 (for the ULM-55Xi type).
IV. Putting the unit into operation
The ULM-55N type: switch on the power supply (12-30 VDC).
The ULM-55Xi type: switch on the intrinsically safe isoating repeater (IRU-420).
V. Setting
up
The level meter is set up by following steps. Use the adjusting elements located under the cap nut to set the
unit up – see fi gure 4.
Procedure:
1. Level meter is connected to the supply line via a miliampere meter (controller, etc.).
2. Disconnect the connector for access to adjusting elements and unscrew the cap nut (mind the internal wires).
Connect again the connector.
3. Empty the tank to the minimum level or put the level meter to the corresponding distance. Set the static current
by
"4 mA"
trimer to 4 mA.*
Turning to the right (clockwise) increases the current, while turning to the left decreases the current.
4. Fulfi ll the tank to the maximum level or put the level meter to the corresponding distance. Set the static current
by
"20 mA"
trimer to 20 mA.*
When it is impossible to fulfi ll the maximum level, then can be used any known (detectable) level and then set
appropriate current by next calculation:
I out = 4 + (0,16 x the level height in %) [mA]
5. To achieve maximum accuracy, it is advisable to re-check the setting of both limit values.
*
The trimmers do not have stop pieces – they can be turned approximately 15 times.
(top view of the internal electronic part)
Figure 2: The inside of the GDM connector
Figure 3: Connection scheme
+U
0V
shielding
Figure 4: Adjusting elements
blue wire
(-)
brown wire
(+)
green-yellow wire
(shielding)
trimer 4 mA
(minimum level
setting)
trimmer 20 mA
(maximum level
setting)
