JUMO 709061 TYA 201 - Single-Phase Power Controller Operating Manual - Manual (Page 85)

2012-12-01/00561071 [SCR Power Controller TYA201] 83
6 Special device functions
6.7 Current limiting
Function Current limiting prevents overcurrents in the load current circuit. It limits the
load current independently of the load resistance and the setpoint value to the
required current limit value by enlarging the phase control angle, if necessary.
Current limiting is unavoidable for heating elements with a high positive tem-
perature coefficient, such as Kanthal-Super, for example. Without current limit-
ing, the load current would accept inadmissibly high values when such heating
elements are in a cold state.
Factory setting Current limiting is not activated.
If necessary, current limiting must be switched on in the configuration level.
v Chapter 5.1.2 "Power controller"
The current limit value can be set both in the configuration level or in the oper-
ator level. In the operator level, it can be adjusted during operation.
H
Current limiting is only possible for power controllers with load current
measurement, i.e. in the order details, subordinate control I, I
2
(code
010 in the order code), or P (code 001 in the order code) must be se-
lected.
The current limiting is implemented via phase angle control. It there-
fore only operates permanently in phase angle control mode.
If burst-firing mode is set, current limiting only operates in the soft
start phase if "With phase angle control" is set as the soft start type.
In three-phase economy circuit, only the current in the strand of the
master power controller is limited to the configured value. As a result
of the economy circuit, significantly greater load currents can flow in
the other two phases.