JUMO 709040 TYA-110 thyristor power unit Operating Manual - Manual (Page 37)

Power units 02.06 37
5 Commissioning
5.5 Load and part-load failure monitoring
This function is only available with the extra code TR or TO. If there is a
change in the load resistance during operation, this is detected and indicated
by the part-load failure monitoring.
The signal output is available either as a floating contact (extra code TR) or an
optocoupler (extra code TO). If a part-load fault occurs, the relay drops out or
the collector-emitter of the optocoupler goes high-impedance. The signal out-
put is also produced if there is a blown fuse.
The response threshold can be set by the front-panel trimmer (6) “load fail” to
a value between 20 and 100% of the rated current for the power unit. Part-
load failure monitoring functions in all operating modes.
v Section 6.2 “Adjustment switches S1 — 21 and pin headers X503 / X504”
5.5.1 Setting the threshold for load failure indication
(Factory setting is 50% of rated load)
h Connect up the load
h Apply full power
h Set the “load fail” trimmer so that the yellow “load fail” LED just goes out.
- turn clockwise (right) = LED lights up
- turn counter-clockwise (left) = LED goes out
h If necessary, the threshold can be reduced by further counter-clockwise ro-
tation, whereby 1.5 turns of the trimmer potentiometer correspond to a load
change of about 10% of the rated curent for the thyristor power unit.
If the load current is below the rated current of the power unit, then the num-
ber of turns required is reduced in the same proportion.
If load current I
L
< 0.5 x I
ThyN
then internal switch S15 must be in position 0.
v Section 6.3 “Summary of possible settings”
H
The load/part-load failure monitoring (low current monitoring) can
also be used for overcurrent monitoring. To implement this, remove
the two jumpers on pin header X504, next to the “angle set” trim-
mer, turn them through 90° and replace.