The Alarm Output on the pulse isolator can be switched off (open contact) or programmed with following options:
The “1:1” option selection is available only if the input source is configured for current or voltage pulses and the relay contact will close when the input signal is above the input signal threshold specified in the data sheet.
The “LFD” option selection is available only if the Input source is configured for switch/proximity detector and the relay contact will close when the input conditions are below the limits specified in the standard EN 60947–5–6.
For the “simple trip output” option, the input signal is compared with a preset value (the threshold value) and the result drives the alarm state. In the case of the input signal value being above the threshold value, the alarm relay contact will close and correspondingly in the case of a signal lower than the threshold value the relay contact will open. In the case of power off or a disturbance of the converter the connection is interrupted and therefore the relay is turned off. To avoid an unstable binary signal with small input value variation, hysteresis of the switching levels is implemented.
The threshold value and the hysteresis can be programmed as a percent of the signal range configured. The permissible settings must fulfil the following conditions:
- threshold value 0.3 to 99.7[%] of the measuring range (*)
- hysteresis 0.1 to 10.0[%] of the measuring range
(*) the threshold output range will be narrowed with growing hysteresis
The “window trip output” option allows specification of two thresholds and can be used for interpretation ”true = inside threshold range” or “false = outside threshold range”.
The Alarm Output can be also inverted by selecting the option ‘Inverted Output’ for the configuration. Note also that the alarm output can be disabled by the status of the Inhibit input.
The figure below shows input and output signal examples for both trip output options: