JUMO TYA 202, Operating Manual, Page: 81 / 108

2011-07-01/00561073 [SCR Power Controller TYA202] 79
6 Special device functions
6.6 Resistance limitation (R control)
.
Function It operates both in burst-firing mode and phase angle control.
If the current measured value for resistance exceeds the resistance limit,
it is
limited by phase angle control or limitation of the switched sine waves.
Limitation of the
power The resistance limitation parameter can be used to activate a limitation of the
power output depending on the resistance value R when operating molybde-
num disilicide heating elements in order to prevent overheating of the heating
element in the upper temperature range. By measuring the resistance of the
heating elements it is possible to assign a precise heating element tempera-
ture.
If the load resistance exceeds this value, it is limited by phase angle control or
limitation of the switched sine waves. This protects the heating element from
overheating.
H
This is only possible in power controllers with current and voltage
measurement that are fitted with cascade control P (Code 001 in
the order code) and only functions for load resistors with positive
temperature coefficient.
In three-phase economy circuits, no direct resistance limitation is
possible because the individual resistance value is not recorded.
However, the limiting function itself can be applied.