HYDAC HLB 1300 - Manual (Page 19)

User Manual HYDACLab ® 23.10.2008
4
4. Function
HYDACLab
®
sensors are compact, multi-functional sensors for determining the condition of fluids
online. The user is kept informed of changes in fluid condition as they occur and can immediately
change the operating conditions accordingly.
Changes in fluid condition that might occur due to ageing or mixing with other fluids, for example,
are indicated by measuring the temperature, relative humidity and the relative change in dielectric
constant (also referred to as DC).
These measurements are available as analogue signals and/or switching signals at the electrical
output of the HYDACLab
®
(e.g. for activating warning devices or alarms).
For information on further output possibilities (e.g. modular connection to a PLC control) please
see our website http://www.hydac.com under "Downloads", "Electronic" or contact the appropriate
HYDAC agent.
4.1 Switching output (standard modification 000)
The NC switching output acts as a warning signal triggered by critical changes in the fluid
condition.
The switching output will switch whenever any of the following changes in measured values
occurs (the values stated are standard factory settings):
Relative change in dielectric constant
± 15 % (temperature compensated)
Relative humidity ≥ 85 %
Temperature ≥ 80 °C
To activate the switching output the relative change in dielectric constant is evaluated
mathematically. It is therefore possible that the analogue values at the time of switching will
differ from the switching thresholds given above.
If as a result of part-filling or re-filling the system, the values for the relative change in dielectric
constant return permanently to a window of
± 10 %, the switching output is deactivated again.