gefran GTF-Xtra Installation And Operation Manual page 19

BF
variable cycle time (GTT)
This mode controls power on the load via a series of conduction ON and non conduction OFF cycles.
The ratio of the number of ON cycles to OFF cycles is proportional to the power value to be supplied to the load.
The CT repeat period is kept to a minimum for each power value (whereas in ZC mode the period is always fixed and not
optimized).
A parameter bF.Cy defines the minimum number of conduction cycles settable from 1 to 10.
In the following example, the parameter = 2.
Figure 21
HSC
Half single cycle
This mode corresponds to Burst Firing that manages ON and OFF half-cycles. It is useful for reducing the flickering of
filaments with short/medium-wave IR lamp loads. With these loads, to limit operating current with low power, it is useful to
set a minimum power limit (for example, Lo.p = 10%).
NB: This mode is NOT allowed with inductive loads (transformers) It is used with resistive loads in single-phase, star
with neutral, or open delta configuration.
Figure 22
Advanced single-cycle
80994B_MHW_GTF-Xtra_05-2016_ENG
Example of operation in BF mode with power equal to 50%
Example of operation in HSC mode with power at 33 and 66%
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