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Nivotemp NT 64D, Nivovent NV 74D
After removing the float, where applicable, be sure the mag-
net inside the float is above the fluid level. This can easily be
verified with a piece of iron to determine the magnet position
inside the float.
DANGER
Electric voltage
Risk of electric shock
When connecting devices, please note the maximum voltages
and currents currents (see technical data) and use the correct
wire cross-sections and circuit breakers.
When selecting the connection lines, also note the maximum
operating temperatures of the devices.
Installation in special areas of application:
If the device will be installed outdoors or in wet areas, the
maximum operating voltage is max. 16 V DC effective or 35 V
DC.
The flange-mounted display units can be swivelled vertically
by approx. 270° so they are easier to read. Please note the
built-in swivel stop. You will notice more resistance when
reaching the stop. Turning it beyond this stop may damage
the display unit.
Flange mounting
NOTICE! The description of how to mount the flange is
merely a recommendation!
Please use the mounting screws provided to mount the
flange! The mounting screws should be tightened to a torque
between 3 Nm and 4 Nm. For sensors with flange housing and
vent filters, the mounting screws should be tightened to a
torque between 2 Nm and 3 Nm. The mounting screws should
be tightened as follows:
Four screws
Five screws
4.2 Electrical connections
Electricity is supplied via plug connectors. Please refer to the
appendix for installation dimensions, nominal voltage and
plug configuration.
The temperature switching outputs are PNP transistors (see il-
lustration):
Supply voltage
BX100018 ◦ 02/2024
Note: When measuring the switching output with high-load
measuring device inputs or when used as a frequency output,
the load must be set to 10 kΩ between the output and earth
(GND) to avoid faulty measurements.
4.3 Information on the correct operation of reed
contacts in Bühler level switches
Based on their construction, reed contacts are very long last-
ing and reliable components. Yet the following should be con-
sidered when using them:
Life of reed switches
The life of reed switches can be up to 10
by high stress and / or incorrect or the absence of protective
circuits when switching inductive, capacitive or lamp loads.
It's therefore important to ensure NEVER to exceed one or sev-
eral of the maximum approved limits, even temporarily, and
to install a contact protective circuit for loads which are not
purely ohmic. Using test lamps when installing the devices is
also prohibited, as these can temporarily allow too much cur-
rent to flow, which can damage the reed contacts. In this case
non-volatile testing equipment should always be used.
Contact protective circuits for reed switches
For direct current voltage a recovery diode per figure A must
be connected parallel to the contact.
For alternating current voltage an RC circuit per Figure B and
Table 1 must be connected parallel to the contact.
A
Contact
Load in VA
Voltage at
contact V
24
60
110
Six screws
230
Please note the max. voltage/load ratings of the respective
level contacts!
Voltages and currents
All Bühler level contacts with reed switch can switch minimal
Switching voltages of 10 µV and minimal switching currents
of 1 µA.
The maximum values specified for the respective contact
types apply.
Level contact with reed switches can therefore be used for SPS
applications as well as for high loads (within the maximum
limits) without hesitation.
9
B
Contact
Load
Recovery diode
10
25
R/Ohm
C/µF
R/Ohm C/µF R/Ohm C/µF
22
0.022
1
120
0.0047
22
0.022
470
0.001
120
0.0047
470
0.001
470
0.001
Bühler Technologies GmbH
cycles. This is reduces
Load
RC circuit
50
0.1
1
0.47
1
0.1
22
0.022
120
0.0047
11
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