MR MESSKO COMPACT MT-ST160SK Manual Del Usuario página 18

6 Adjustment of the gradient
Fig. 6
The heating current I which flows through the heating resistor
H
(Fig. 6) is the determining factor for the required gradient.
Read the heating current (to be set) from the setting curve
(Fig. 7) corresponding to the required temperature gradient.
The heating current is determined via the voltage drop on an
internal 1Ω resistor. On the 1Ω resistor measure the dropping
voltage on terminals 4 and 5 (Fig. 5) with a high-ohmic
voltage meter (not a current meter) set to „V". The voltage
value measured in „V" corresponds to the value of the heating
current in „A".
Set the value for the heating current on the setting screw for
the adjustment resistance (Fig. 3/2). Turn the screw to the right
and the heating current rises. Turn the screw to the left and
the heating current falls.
Check the set temperature gradient based on the temperature
value read at the beginning. If the temperature reference value
is not reached after approx. 30 min., a readjustment can be
made on the potentiometer. Also here, remember to provide
a heat-up or cool-off period (approx. 15 min.). After the
adjustment has been made, remove the power source and the
voltage meter.
6.2 Adjustment via resistor value MT-ST160WR
The determining factor for the required gradient is the internal
resistance of the circuit as shown per Fig. 8 at a given nominal
CT current.
Establish the value of resistance to be set from Fig. 10 using
the given nominal CT current and required gradient.
Example:
nominal CT current:
required gradient:
resistance value from curve:
18
1,8A
21K
8,0Ω
Remove the bridge (Fig. 9/1) between terminal 4 and 5 and
measure the resistance value between these terminals. Set
the value by means of the screw (Fig. 9/2). Clockwise rotation
causes the value to rise, anticlockwise and it falls.
After setting, do not forget to replace the bridge between
terminal 4 and 5.
CAUTION
The accuracy according to which the resistance value is
adjusted depends significantly on the quality and the error
of the measuring instrument applied.
We strongly recommend the use of an ohmmeter for
gradient adjustment.
Fig. 8
Fig. 9
BA 2038/02/07