JUMO 709061/8-01-032 Operating Manual page 91

Which
operating mode
is suitable for
which load?
V1.04/EN/00561071 [Thyristor Power Switch TYA 201]
Silicon carbide heating elements have a nominal resistance that can increase
by a factor of 4 over the long term. So when dimensioning a system it is nec-
essary to adapt the power controller to produce twice the power for the heat-
ing elements. This doubles the current for the thyristor power controller.
Old = old state of the heating element
New = new condition of the heating element
The relationship is illustrated by the following formula:
P = U
Neu Neu
P control is also used for free-running economy circuits running off a 3-phase
supply network.
Operating mode
Phase-angle control
Phase angle control
with
current limiting
Burst-firing operation
Burst-firing operation
with α start
Burst-firing operation
and current limiting
Subordinate control
loop
2
U
2
I
P
6 Special device functions
U
Alt
• •
I = -------- - 2I
Neu Alt
2
Resistive load
TC constant TC positive
X
X
X
X
X
X X
R
R =
-------- -
New
•
= U I = P
Alt Alt Alt
TC nega- Long-
tive term ag-
ing
X X
X X
X
X
Alt
4
(12)
Inductive
load
X
X
X
X
X
89