6 CLIO PROTECTION
To help with monitoring the condition of a power systems, various transducers such as vibration monitors,
tachometer
s, voltage, current and pressure transducers can be used to extract useful metrics from the system.
Such transducers work by converting the measured data into currents, which can then be fed into instrumentation
device such as meters or IEDs. This mechanism is called CLIO protection. CLIO stands for Current Loop Input
Output.
Transducers have current ranges associated with the full scale of what they are measuring. Typically these ranges
are 0-1 mA, 0-10 mA, 0-20 mA, or 4-20 mA.
Note:
Do Not select CLIO options if CLIO board is not fitted.
6.1 CURRENT LOOP INPUT IMPLEMENTATION
Four analog current loop inputs are provided for transducers with ranges of 0 – 1 mA, 0 – 10 mA, 0 – 20 mA, or 4 –
20 mA
. Each input can be configured to accept any one of these ranges. Associated with each input are two
protection stages; one for alarming and the other for tripping. Each stage can be individually enabled or disabled
and each stage has a definite time delay setting.
Each current loop input may beset to alarm for an 'over' condition or an 'under' condition. You do this with the
setting CLI Alarm Fn and selecting under or over as appropriate. Likewise, each CL input may be also set to
trip for an 'over' condition or an 'under' condition. You do this with the setting CLI Trip Fn and selecting under or
over as appropriate. The sample interval is nominally 50 ms per input.
The relationship between the transducer measuring range and the current input range is linear. The maximum and
minimum settings correspond to the limits of the current input range. This relationship is shown below. The
diagram also shows the relationship between the measured current and the analog to digital conversion (ADC)
count. The hardware design allows for over-ranging, with the maximum ADC count corresponding to 1.0836 mA
for the 0 - 1 mA range, and 22.7556 mA for the 0 - 10 mA, 0 - 20 mA and 4 - 20 mA ranges. The device will
therefore continue to measure and display values beyond the Maximum setting, within its numbering capability.
P64x Chapter 7 - Transformer Condition Monitoring
P64x-TM-EN-1.3 159
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