Samson TROVIS 6400 - Limit Contacts; General Definition

5.2 Limit contacts (
Y
=
0
or
2
)
5.2.1 General definition
Each limit contact (
Y1
and
Y2
) can, independent of one another, be assigned a value. This value
can be monitored to determine whether it is exceeded in either direction. Limit contacts are as-
signed using configuration block
Y1
(switching output
Y1
) and configuration block
Y2
(switch-
ing output
Y2
).
The limit value is set in the paramterization level as a percentage using parameter
1A
or
2A
.
This is set absolutely (assignment to input signal X) or as a percent (assignment to an internal
signal Y or XD) using parameter
1A
or
2A
, resp.
A limit contact, similar to an on-off controller output, contains a differential gap which is set as a
percentage with parameter
1H
or
2H
, referring to the range of the monitored variable.
The limit alarm contact basically contains two circuit states (closed/opened), triggered by
means of a snap-action element. If the switching condition of the limit value is satisfied, the
switching output is closed; otherwise it is open.
Fig. 10 clarifies the behaviour of the activated limit alarm contact
Y1
or
Y2
when it is exceeded
in either direction. The controller output is disabled up to a set limit value. After limit value
1A
is
exceeded - minus the differential gap
1H
-, the limit contact is open.
Underrange of a limit value is monitored analogous to that of an exceeded limit value. The con-
troller output remains disabled until the limit contact is reached. After the limit value has been
fallen short of, the contact is closed. As soon as the limit value plus differential gap has been ex-
ceeded, the contact is opened.
Fig. 10 ⋅ Limit contacts with snap-action element
Y1/2
Y1/2
On
Off
When limit value exceeded
When limit value fallen short of
On
Off
Monitored variable
(X, XD, Y)
1A or 2A
Limit value
1A or 2A
Limit value
1H or 2H
Differential gap
1H or 2H
Differential gap
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