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Important Safety Notes
No user serviceable parts are contained within
the equipment. All repairs must be performed
only by the manufacturer. Misuse or any
attempted modification of the equipment will
lead to considerable safety risks!
Purpose
Measuring transducer with output of a level-
proportional stabilized current 0 to 20 mA or 4
to 20 mA with the level probe type NRG 21 or
NRG 26. Application for continuous measuring
of levels and remote level indication.
Technical Data
Type-approval No.
TÜV · WR/WS · 99-317
Input
Three connections for NRG 21 or NRG 26 or
for input current 0 . . . 1 mA at 6.8 kΩ
Output
Stabilized current 0 . . . 20 mA or
4 . . . 20 mA by external wire link
Adjustors
Two adjustors for zero point and measuring
range
Indicators
One meter, 40 x 40 mm, scale 0 . . . 100 %
Mains supply
24 V, 115 V, 120 V, 230 V, 50 . . . 100 Hz,
3,5 VA.
24 VDC supply also possible with the ancillary
unit type URN-1.
Protection
IP 40
Permissible ambient temperature
0 . . . 55 °C
Case materials
Base: ABS plastic, black
Cover: polystyrene (highly shock-resistant),
stone grey
Approx. weight
0,5 kg
Dimensions
See Fig. 1
Installation of Level Transmitter
Design "b"
On supporting rail (with mounting clip)
1. Snap level transmitter onto supporting rail.
G
2. Loosen cover screws
and unplug cover
A
G
G
from its base
(see Fig. 1).
B
C
G
3. Select cable entry
and remove corre-
D
sponding seal.
On mounting panel
G
1. Loosen cover screws
A
and unplug cover
G
G
from its base
(see Fig. 1).
B
C
G
2. Unscrew mounting clip
E
.
G
3. Drill the hole
marked in the base to
F
4.3 mm dia.
4. Fasten base with two screws M4 onto
mounting panel.
G
5. Select cable entry
and remove corre-
D
sponding seal.
Notice
To provide sufficient ventilation, ensure a
minimum spacing of 20 mm between adja-
cent units.
Wiring
Wiring should be carried out in accordance
with wiring diagram, Fig. 3.
For wiring to the probe screened four-con-
ductor cable is required, e.g. 4 × 0.5 mm
max. cable length ≤ 100 m.
Important Notes
I
If further units such as NRR 2-1 or NRS 2-1
are connected in parallel to the level trans-
mitter, only a single resistor R M is used.
The others must be removed (Fig. 4).
I
Connect screen only terminal 10 of the
level transmitter, but not at the probe.
I
The screen must not make any other electri-
cal contact.
I
The mains voltage is indicated on the name
plate.
Initial Adjustments
Step 1
Adjustment of zero point (0 %)
–
1. Turn adjustor „B"
(Fig. 2)
2. Fill vessel to initial level required (0 %)
—
3. Turn adjustor „A"
indicates 0 %.
Step 2
Adjustment of measuring range (100 %)
1. Raise level in vessel to final level required
(100 %).
–
2. Turn adjustor „B"
˜
meter
indicates 100 %.
3. Repeat adjustment of zero point (Step 1).
Performance Tests
1. The supply voltage of the level probe type
NRG 21 and NRG 26 is 12 VDC and can be
measuring between terminals 3 and ⊥ of
the probe.
2. The level-proportional current is a direct
current lying between 0.2 mA and approx.
1 mA and can be measured by connecting
the measuring instrument between terminal
1 of the probe and terminal 11 of electronic
control unit. If this current is considerably
higher than 1.2 mA check wiring or probe.
3. The level-proportional voltage is a direct
voltage lying between 0.5 V (min) and 7 V
(max) and can be measured between termi-
nals 1 and ⊥ of the probe.
2
,
Important Notes
I
If the medium to be controlled has the ten-
dency to the form deposits (lime, corrosion
products) the adjusted values are modified.
The level indicated is then higher than the
actual level. In this case the probe should
be cleaned at regular intervals. Remove
electrode. Attention: Ensure that vessel is
not under pressure. It suffices to wipe the
Teflon insulation with a damp cloth.
I
When switching off inductive loads, voltage
spikes are produced they may impair the
operation
of
control
systems. We therefore recommend that
inductive loads are provided with commer-
cial arc suppreossor RC combinations, e.
g. 0,1 µF/100 Ω.
10 turns to the left
˜
until the meter
to the right until the
and
measuring
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