WIKA 73 Betriebsanleitung Seite 9

7. Alarm contacts
T Electrical connection should only be carried out by qualified electricians.
T The switches are terminated on screw terminals within the terminal box.
T Conductor cross-section max. 1.5 mm
T The terminal assignment is stated on the connection plate of the
thermometer.
To adjust red set pointers
The red set pointers for the alarm contacts are adjustable via the adjustment
lock on the window using an adjustment key (included in delivery; on standard
gauges this is found on the outside edge of the junction box).
Red set pointers
Adjustment lock
The red set pointers for the alarm contacts are adjustable over the full range of
the instrument. Switching points should be set in the range between 10 % und
90 % of the full scale, to ensure switching accuracy and the long life of the
measuring mechanism.
7.1 Magnetic snap-action contact Model 821 and sliding contact Model 811
Magnetic snap-action or sliding contacts are control switches which make or
break connected electric circuits as the contact arm, moved by the measured-
value pointer, reaches the appointed set-point.
Surface oxidation at the contact points may lead to malfunction, which can
result in contact-arcing, particularly in the case of intrinsically safe circuits (low
voltages and currents), and in the case of relatively high contact loads.
WIKA Operating instructions gas actuated thermometers
.
2
Adjustment key -
removable
GB
9