Functional Test; Functional Test Description; Functional Test Procedure; Test In The Event Of A Fault - Pentair Raychem NGC-20-C-E Guide D'installation, D'utilisation Et De Maintenance

4.5 Functional test

4.5.1 Functional test description

4.5.2 Functional test procedure

4.5.3 Test in the event of a fault

4.6 Safety Integrity level

INDUSTRIAL HEAT TRACING SOLUTIONS
The Raychem NGC-20-CL-E units are meeting the requirements of SIL2 (see paragraph
4.6 for more details) accordingly to IEC 61508-1:2000 and IEC 61580-2:2000 In this
standard is stipulated that in order to guarantee safe and reliable operation the units
need to be subjected to a functional test at regular intervals. In the case of the Raychem
NGC-20 limiter this is set at 12 months (1 year) intervals. These tests must be performed
according to the guidelines provided. When the operational lifetime has expired, the
systems no longer conform to the requirements of their SIL certification.
Type SIL level
NGC-20-CL-E SIL 2
Table 3: Functional test
In general the functional test always starts from the "normal" state, meaning that there
should not be any alarms present on the unit and that the limiter tripped LED (Lim
Tripped) on the display of the unit should not be lit. In case the Lim Tripped LED is ON
than the unit should be reset before the functional test is being performed. Apart from
the scheduled test intervals a functional test is to be performed after every malfunction of
the system and each time the limiter set point has been changed.
The following steps should be executed as part of the functional test:
• Disconnect one of the leads of the temperature sensor of the limiter RTD. (RTD 3
limiter)
• The red alarm LED "Lim tripped" should light up momentary and the output of the unit
should switch OFF.
• Re-establishing the sensor connection has no immediate effect. Switch off the mains
supply of the unit and leave the power off for one minute. Powering up the unit again
should not reset the limiter.
• After the Limiter reset button is been pressed the Lim Tripped alarm will go away and
switch the output on. (Assuming the measured temperature is below the set point
temperature and there are no other faults)
• Install a wire bridge, short cutting the limiter sensor terminals marked with R+ and R-
(RTD 3 Limiter)
• The red alarm LED "Lim tripped" should light up momentary and the output of the unit
should switch OFF.
• Removing the wire bridge has no immediate effect.
• Switch off the mains supply of the unit and leave the power off for one minute.
Powering up the unit again should not reset the safety limiter.
• Only after the Limiter reset button has been pressed will the Lim Tripped alarm go
away and switch the output on. (Assuming the measured temperature is below the set
point temperature and there are no other faults)
In the event of a system fault, the instrument switches off the load. This condition
is indicated by the LED "Lim tripped" which will light up. The fault is signalled
simultaneously by the alarm relay which changes state. Press the reset button (at least
2 sec) until the "Lim. Tripped" LED dims. If the safety circuit remains open, the system
and the probe circuit have to be checked. Press the reset button again. If the instrument
remains inhibited after pressing the reset button the unit should be replaced.
The safety integrity level of the Raychem NGC-20 is SIL2. The SIL level can be achieved by
determining the following safety related parameters:
1. PFDavg: The average probability of the hazardous failure of a safety function when it is
demanded;
2. HFT: The hardware fault tolerance;
3. SFF: The fraction of non-hazardous (i.e. safe) failures
See for details on the Raychem NGC-20-CL-E table Table 4.
ML-RaychemNGC20CLE-IM-INSTALL130 Rev8
Proof check interval Unit Lifetime
1 year 25 years
18 / 95