gefran GFX4-IR Series Installation And Operation Manual page 43

DT - "Delay triggering" (for ZC, BF control modes only)
Settable from 0° to 90°.
Useful for inductive loads (transformer primaries) to prevent current peak that in certain cases could
trip the high-speed fuses that protect the SCRs.
Figure 61
To conduct inductive loads controlled in PA mode, do not use delay triggering; instead, use the phase Soft-Start ramp.
Figure 62
Example of phase ramp to fire a
transformer in PA mode
Comparison of method to fire a transformer: Soft-Start Ramp (for PA mode) / Delay triggering (for ZC and BF mode)
80404L_MHW_GFX4-IR_03-2020_ENG
Transient with
Over-Current
Example of firing of inductive load with/without delay-triggering.
Transient without
Over-Current
Example of firing with Delay-
Triggering of a transformer in ZC
mode
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