MR MESSKO COMPACT MT-ST160SK Manual Del Usuario página 17

5 Indication control and readjustment
6 Adjustment of the gradient
To check the microswitches which are located to the right
of the pointer, turn the pointer clockwise by hand past the
microswitches and back. A return spring pulls the pointer back
to its original position (Fig. 4).
CAUTION
Do not release the pointer here. It must be slowly returned
to its original position. If the pointer snaps back, the
microswitches may be damaged.
To check the microswitches which are located to the left of the
pointer slide them clockwise past the pointer (as when setting
the microswitches). After checking, the microswitches must be
reset to their original position.
CAUTION
The pointer must never be turned anti-clockwise to lower
temperatures. This will damage the measuring system.
5 Indication control and readjustment
The pointer thermometers are calibrated at the factory. If it
is necessary to readjust it, indication control and comparison
measurements should only be carried out in moving water
baths whose temperature remains constant for several minutes
(approx. 15 min.). Readjustments are possible. The adjustment
screw (Fig. 1/3) is on the front of the instrument.
CAUTION
The pointer thermometers are calibrated and set at the
factory. Readjusting them results in the loss of accuracy as
well as the guarantee for the device.
6 Adjustment of the gradient
The winding temperature (thermal image) is simulated with a
heating resistor (see chapter 2.2), which has to be fed by the CT
( secondary current transformer) of the transformer.
Therefore the required gradient depending on the nominal CT
current (temperature difference between winding and oil at
nominal load) must be known.
BA 2038/02/07
CAUTION
For nominal CT currents above 2A up to 5A or below 2A you
have to use additionally the multi-ballast transformer (BA2093).
According to IEC 354 this thermometer can be operated at an
overload of upto 3A input current for the period of 0,5h.
Factory-made setup:
Nominal CT current:
Temperature gradient:
Heating current (MT-ST160W):
Heating resistor (MT-ST160WR):
If a different setting is required, this must be performed
yourself.
6.1 Adjustment via heating current MT-ST160W(TT)
Before the temperature gradient is set, the temperature value
should be read from the scale and noted. Make sure that the
sensor temperature remains constant during the adjustment.
Connect a constant power source to terminals 3 and 6
(Fig. 5) which supplies the heater with the nominal CT
current I (e.g. 2A).
W
Fig. 5
2 A
17K
1A ± 5%
6 Ω
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