7300A User Manual
3-4
3.3. SINGLE-CYCLE (code FC1)
‘Burst mode’ firing with a single firing or non-firing cycle is known as ‘Single-cycle’.
For example, with a setpoint of 50% (corresponding to a duty ratio
η
= 50%) the modulation
comprises 1 firing cycle and 1 non-firing cycle.
For duty ratios
η
< 50% the firing time remains unchanged (1 cycle) and the non-firing
time increases.
For duty ratios
η
> 50% the non-firing time remains unchanged (1 cycle) and the firing
time increases.
Firing modes
3.4. ADVANCED SINGLE-CYCLE (code ASC)
In order to reduce power fluctuations during firing time, ‘Advanced single-cycle’
thyristor firing mode uses:
• a whole number of cycles for firing, and
• a whole number of half-cycles for non-firing, and.
Important: ‘Advanced single-cycle’ firing mode is only available for 4S or 6D three-phase
load configuration.
For duty ratios
η
< 50%:
- the thyristor firing time is set to one cycle
- non-firing occurs for half-cycles.
For duty ratios
η
> 50%:
- the non-firing time is set to half a cycle,
- firing occurs for whole cycles.
By using half-cycles for non-firing time, the modulation time is reduced compared with
standard ‘Single-cycle’ mode, which is equivalent to burst mode with one cycle.
‘Advanced Single Cycle’ mode (Code ASC) reduces flicker on short wave infrared elements
and is thus less annoying on the eyes.
t
66.6% power
(F= 2 T
NF
)
T
M
T
F
T
NF
t
T
M
T
F
T
NF
•
Standard single-cycle
(T
F
or T
NF
= 1 cycle)
•
Advanced single-cycle
(T
NF
= 0.5 cycles: T
M
reduced)
66.6% power
(T
F
= 2 T
NF
)
Figure 3-4 Exemple of Single-cycle and Advanced sigle-cycle firing mode
