User manual

System 182-XT-4 Relay outputs
6 - 5
ba76027e02 12/2014
6.3 Basic information on relay functions
This chapter describes general basic information concerning the
following relay functions:
 Monitoring (see section 6.3.1)
 Limit indicator (see section 6.3.2)
 Proportional output (see section 6.3.3)
6.3.1 Monitoring
When using a relay for monitoring, a relay action (Open, Close) occurs
when certain states occur. This function is suitable, for example, for the
monitoring of errors in the system.
6.3.2 Limit indicator
With a limit indicator, a relay switches when a specified limiting value is
exceeded or undercut.
Limit indicators can be used in the following way:
 Monitoring a limiting value using a relay:
when a limiting value (upper or lower limiting value) is exceeded or
undercut, a relay switches. The Open or Close relay actions are
possible in each case (see page 6-6).
 Monitoring two limiting values using two relays:
If the upper limiting value is exceeded or undercut, a relay switches,
and if the lower limiting value is exceeded or undercut, another relay
switches. The Open or Close relay actions are possible in each case
(see page 6-6).
For monitoring functions, use the relay preferably as an
opener. In the case of an error, the relay opens. As a result,
the monitoring function operates even if, for instance, the
supply voltage fails.
If the simple monitoring function (Open, Close) with one or
two relays is not sufficient, use proportional output (see
section 6.3.3).