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Quick current changes, which may for instance occur in case of partial.
Quick current changes, which may for instance occur in case of partial short-circuit, may be
detected by overcurrent monitoring (max., a – a‘).
Quick current changes, which may for instance occur in case of load breakdown may be detected
by undercurrent monitoring (min., c – c‘).
NOTE FOR LOAD MONITORING:
Changes of the burden resistor and parameters can be necessary in case of small load currents or
small current fl ow angles (i. e. small phase angles).
If a Thyro-P 3P is used in phase-angle operating mode, the star point of the load and the star point
of the (built-in) voltage transformers should be connected together to ensure an accurate load
monitoring. Please contact us in case of need..
The values in the following table apply to ohmic loads.
Different values apply may be required for specific hea-
ting resistors, for instance IR radiators. The adjustable %
values shown in the tables are load current variations on
the present operating values.
HEATING 1P 2P*/3P 3P
ELEMENTS
IN PARALLEL STAR CONNECTION STAR CONNECTION DELTA STAR CONNEC-
FOR EACH WITH SEPARATE WITHOUT CONNEC- CONNECTION TION WITH
STRAND STARPOINTS TED NEUTRAL CONNECTED
CONDUCTOR NEUTRAL CONDUCTOR
5 10% 10% – – 10%
4 13% 13% 10% – 13%
3 17% 17% 13% 10% 17%
2 25% 25% 20% 12% 25%
1 50% 50% 50% 21% 50%
* for Thyro-P 2P: additional external converters in phase L2 are possible.
Star connection
with separate star points
Star connection
without neutral conductor
TAB. 2 PARTIAL LOAD BREAKDOWN WITH HEATING ELEMENTS SWITCHED IN PARALLEL,
UNDERCURRENT, RELATIVE MONITORING
Delta connection
Star connection
with neutral conductor