Electrical Connections; Information On The Correct Operation Of Reed Contacts In Bühler Level Switches - Bühler technologies Nivotemp 61-0-WW Serie Guía Rápida

Nivotemp 61-0-WW
This is particularly important for the bottom water alarm
float when inserted in the collecting basin (optional) (also see
installation principle). In this case, be sure to tighten the
screws evenly so the level switch is not tilted (resulting in the
bottom float tilting in the basin and not working).
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.
Installation principle
Oil
Water
min.ø65
(tank inside ø)

4.2 Electrical Connections

The device must be installed by an authorised professional fa-
miliar with the safety requirements and risks. Be sure to ob-
serve the safety regulations and generally applicable rules of
technology relevant for the installation site.
Please refer to the compatibility charts in the appendix for the
pin assignment and the electrical data. Proceed as follows: Se-
lect the plug type, contact type and number of contacts (per
your order).
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.
6 Bühler Technologies GmbH
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.
welded on collecting basin
with welded sleeve G3/4
Drain valve
(not included with
collecting basin)
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.
Contact material
All reed switches in Bühler level contacts use rhodium as the
contact material for the actual contact areas.
9
cycles. This is reduces
Magnetic fields
Avoid external magnetic fields, including from electric mo-
tors. These can interfere with the function of the reed
switches.
Mechanical loads
Do not expose the level switch to strong blows or bending.
A
Contact
Load
Recovery diode
Load in VA 10
Voltage at R/ C/µF
contact V Ohm
24 22 0.022
60 120 0.0047
110 470 0.001
230 470 0.001
B
Contact
Load
RC circuit
25 50
R/ C/µF R/ C/µF
Ohm Ohm
1 0.1 1 0.47
22 0.022 1 0.1
120 0.0047 22 0.022
470 0.001 120 0.0047
BX100007 ◦ 05/2022