Table of Contents
Advertisement
NOTES: USE WITH INDUCTIVE LOADS AND TRANSFORMERS
a) Connect a varistor (MOV) between each wire of the primary transformer and ground.
Varistor data: rated voltage 660Vrms,..., 1000Vrms; minimum energy 100J
b) The maximum current controllable by the device is less than the product's rated value (see technical data).
c) In ZC and BF trigger mode, use the Delay-triggering function to limit peak magnetization current.
d) In PA trigger mode, use the Softstart function.
e) DO NOT use HSC trigger mode.
f)
DO NOT connect RC snubbers in parallel to the transformer primary.
g) Select the inductive load using the Hd.1 parameter (ref. Software manual)
Trigger modes
The GTF has the following power control modes:
- modulation via variation of number of conduction cycles with zero crossing trigger.
- modulation via variation of phase angle.
Zero Crossing mode
This function eliminates EMC noise. This mode controls power on the load via a series of conduction ON and non
conduction OFF cycles.
ZC -
constant cycle time (Tc ≥ 1 sec, settable from 1 to 200 sec)
Cycle time is divided into a series of conduction and non conduction cycles in proportion to the power value to
be transferred to the load.
Figure 36
For example, if Tc = 10sec, if the power value is 20% there is conduction for 2 sec (100 conduction cycles @ 50Hz)
and non conduction for 8 sec (400 non conduction cycles @ 50Hz).
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).
80960_MHW_GTF_01-2012_ENG
25
Advertisement
Table of Contents
