JUMO 709062 TYA 202 - Three-Phase Power Controller Operating Manual - Manual (Page 69)

2012-12-31/00561073 [SCR power switch TYA202] 67
6 Special device functions
6.1 Detection of load faults
The load monitoring function can detect and signal a load failure, partial load
failure, or a partial load short circuit.
Undercurrent This function is used for one or more heating elements connected in parallel
that are to be monitored for breakage.
Overcurrent This function is used for several heating elements connected in series that are
to be monitored for short circuits.
Function This function does not only take the decreasing or increasing load current into
consideration but also includes the load voltage in the monitoring process.
The correct load ratios of the system are saved during Teach-In.
Based on this status, the load changes are continuously monitored irrespec-
tive of the required output level. In the event of a breakage or short circuit of a
heating element, the load current increases or decreases. This is detected by
the load monitor and a load fault is signaled.
Limit value A limit value must be entered in the configuration or operator level in % for the
load monitor. This limit value depends upon the number of heating elements
connected in parallel or in series.
For heating elements with a high positive or negative temperature coefficient,
a suitable limit value must be determined independently. The values in % giv-
en below (see arrow) are used for this purpose.
A value in % is displayed for each of the three phases, which represents the
current deviation from the Teach-In values as a percentage. Access this win-
dow via Operator level
r
Monitoring
r
Limit value load monit.
H
These values can be used to find out in what phase a load error occurred. If a
load break occurs in phase L3, for example, the value in % exceeds the set
limit value (10 % in the table).