Temperature Setting Secured And Locked To Prevent Manipulation; Changing Limiter Set Point; Procedure To Write New Temperature Set Point To Limiter - nVent RAYCHEM NGC-20-C-E Guide D'installation, D'utilisation Et De Maintenance

4.3.4 Temperature setting secured and locked to prevent manipulation
The lock out temperature (set point) of the safety temperature limiter must be set in such a way that maximum T-class temperature
cannot be exceeded. The surface temperature of the heat-tracing cables is limited to the temperature applicable in this T class -5 K
for temperatures below or equal to 200°C or -10 K for temperatures greater than 200°C. Refer to section 4.4 below for the procedure
to change the safety limiter set point.
Independence from control system
The safety temperature limiter operates totally independent from the temperature control system and has an own temperature
input (RTD Limiter) In case of a defect to any part of the NGC-20 unit the device shall be de-energized before replacing the defective
equipment.
4.4 Changing limiter set point
Changing the set point of the limiter requires the combination of the internal limiter set button and an external user interface.
4.4.1 Procedure to write new temperature set point to limiter
In order to write a new set point to the temperature limiter a safety procedure needs to be followed. Changing the set point of the
temperature limiter requires the combination of the internal limiter set button as is shown in Figure 11 and a programming device. As
programming device one can use; Supervisor software, NGC-UIT2/TOUCH1500 terminal or the handheld configuration and monitoring
assistant CMA2.
The procedure to change the limiter set point is the same for all user interfaces. The configuration tool will write the new set point
to the input buffer of the NGC-20-CL-E controller. Only when the internal temperature set button is pressed will the new set point
be forwarded to the internal memory of the temperature limiter. The limiter set point button needs to be activated within a certain
time after the buffer has been loaded with the new set point. If the button has not been pressed before the programming window
is elapsed, the buffer will be emptied and the old value remains active. Once the new set point has been written the new or in case
the write procedure was not successful the old set point will be read back by the programming device as confirmation to the user.
After changing the limiter set point the user shall verify whether the set point has been updated correctly. The limiter set point can
be shown on the NGC-20 hardware by pressing and holding the black Limiter SET button. While the limiter set point is shown the red
LED indicator marked with LIMITER will blink. After the button is released the display will show the controllers measured temperature
again and the LIMITER LED will go off. Each time after the limiter set point has been altered a functional test as per paragraph 4.5.1 is
to be performed.
Figure 11: Internal Limiter control buttons: Limiter (temperature) SET and Limiter RESET pushbuttons.
RAYCHEM-OM-INSTALL130-NGC20CLE-ML-2204
HEATER
ALARM
LIMITER
RS485
BLUETOOTH
RESET
Limiter reset button (rearm the limiter after it has tripped)
SET
Limiter temperature set button to be pressed after
LIMITER
the polling process has been initiated
nVent RAYCHEM NGC-20
Home
EN
DE
FR
PT
RU
|
nVent.com/RAYCHEM 17