JUMO 709061 TYA 201 - Single-Phase Power Controller Operating Manual - Manual (Page 83)

2012-12-01/00561071 [SCR Power Controller TYA201] 81
6 Special device functions
Silicon carbide heating elements have a nominal resistance that can alter by a
factor of 4 over the long term. So when dimensioning a system, it is necessary
to provide power controllers that can produce twice the (nominal) power for
the heating elements.
This results in double the current for the SCR power controller.
Old = old state of the heating element R
New
=
New = new condition of the heating element
The relationship is illustrated by the following formula:
P control is also used for free-running economy circuits running off a three-
phase supply network.
Which
operating mode
is suitable for
which load?
R
Old
4
----------
P
New
U
New
I
New
•
U
Old
2
---------- 2I
Old
• U
Old
I
Old
• P
Old
= = = =
(12)
Operating mode Resistive load Inductive
load
TC constant TC positive TC nega-
tive Long-
term ag-
ing
Phase angle control X X
Phase angle control
with
current limiting
X X X
Burst-firing mode X
Burst-firing mode with
α
start
X X
Burst-firing mode and
current limiting X X X
Subordinate control
U
2 X X X
I
2 X X
P X X