INSTRUCTION MANUAL
NI-492WE
Rev.4 05/18
3 of 7
The position of the adjusting bush is given in Fig. 2.
Fig. 2 - Adjusting bush and plumbing
Adjustment slot cover
Sealing lead
Stainless steel wire
Adjusting bush
The effect of the sense of rotation of the adjusting bush is shown
on the slot cover. Rotate the bush by inserting a
3mm
dia. rod or
drill into the holes on the bush itself (It recommends using a drill
bit on the side of the shank).
7 - SET POINT CALIBRATION
In order to proceed with the calibration and the periodical
functional verification of the instrument a suitable
calibration
circuit
(Fig. 3) and of an adequate source of heat are required.
The test instrument should have a measurement range
approximately equal to or slightly wider than the pressure switch
range and should have an accuracy consistent with the accuracy
required to calibrate the set point.
Fig. 3 – Calibration circuit
TS -
Temperature switch
TT -
Test thermometer
TB -
Thermostatic bath
7.1 PRELIMINARY OPERATIONS
Slide up the adjustment cover (Fig. 2 item 1).
7.2 CALIBRATION CIRCUIT AND OPERATIONS
Prepare the control circuit as indicated in Fig.3
.
If the instrument is equipped with two contacts, remember that
they are released simultaneously but within the specification
tolerance.
The warning lamps should be connected to the terminals NA or
NC according to the required contact action.
Fig. 4 – Color of wires and function
GDN-Internal grounding connection: color jellow/green
C-Common:
color brown
NO-Normally open:
color blue
NC-Normally closed:
color black
M
icro
1
C-Common:
color gray
NO-Normally open:
color red
NC-Normally closed:
color white
M
icro
2
Contacts status at atmospheric pressure.
C
- Common
NA
- Normally open
NC
- Normally closed
Connection between C and NA
•
If the circuit is open at the workin temperature, the instrument
closes
the circuit when the set point is reached with temperature
on rise
(
closure on rise
).
•
If the circuit is closed at the working temperature, the instrument
opens
the circuit when the set point is reached with temperature
on
fall
(
opening on fall
).
Connection between C and NC
•
If the circuit is closed at the working temperature, the instrument
opens
the circuit when the set point is reached with temperature
on
rise
(
opening on rise
).
• If the circuit is open at the working temperature, the instrument
closes
the circuit when the set point is reached with temperature
on
fall
(
closure on fall
).
The temperature switch must be kept in the normal installation
position, i.e. with the temperature connection downwards.
Modify the temperature in the circuit up to the desired
microswitch set point value.
Using a
3mm
dia. rod drill into the holes on the bush (It
recommends using a drill bit on the side of the shank).
Adjust its position until the relative lamp turns on (or turns off);
then turn it in the opposite direction until the lamp turns off (or
on). Slowly turn the bush again until the lamp turns on (or off)
7.3 SET POINT VERIFICATION
Increase the temperature up to the normal working temperature
(Tw), wait the stabilization of the temperature. Modify, slowly the
temperature up to the set value (Ti) and record the set point
value. Write the set point value on the adhesive label.
Note
: the verification of the repeatability have to be tested
checking the set point (Ti) three times approaching the set point
from the same starting point (Tw). The temperature cycles have
to be performed slowly.
7.4 FINAL OPERATIONS
Disconnect the instrument from the calibration circuit.
Close the adjustment slot by sliding down the slot cover (Fig. 2,
1), then seal with lead the instrument.
Mount on pressure connection the protecting cap supplied with
the instrument. It should be definitively removed only
during
the
connection steps.
8 - INSTRUMENT PLUMBING
The plumbing (see Fig. 2), aimed as a guarantee against
possible tampering of the calibration, can be carried out using a
flexible steel wire (2), 1 mm
2
in section, wound up around the
case in the groove purposely provided.
9 - MOUNTING AND CONNECTIONS
9.1 MOUNTING
Mount instruments with capillary either on pipe or surface by
means of the proper bracket (see Fig. 9 and 10) or direct on plant.
Select a location where possible shocks and temperature
variations remain within tolerable limits.
For the instrument with capillary the difference in height between
bulb and case have not exceeding two meters (fig 11 and 12
distance h).
9.2 INSTALLATION OF TEMPERATURE SWITCH
WITH DIFFERENCE IN HEIGHT BETWEEN BULB
AND INSTRUMENT ENCLOSURE GREATER THAN 2
METERS
9.2.1 TEMPERATURE SWITCHES CLASS SAMA II A
Difference in height between bulb and instrument enclosure
causes a systematic error of set point calibrated value (“bulb
elevation error”). This error can be corrected during calibration
using the table attached to our technical instruction
IS-TC.401E
,
available on request.
