sepam 20 user manual - Schneider Electric

Protection functions Temperature monitoring
ANSI code 38/49T
PCRED301005EN - 06/2008
MT10878
Operation
This protection is associated with an RTD of the Pt100 platinum (100 Ω at 0°C or
32°F) or Ni100 or Ni120 nickel type in accordance with the IEC 60751 and DIN 43760
standards.
b it picks up when the monitored temperature is greater than the Ts set point
b it has two independent set points:
v alarm set point
v tripping set point
b when the protection is activated, it detects whether the RTD is shorted or
disconnected:
v RTD shorting is detected if the measured temperature is less than -35 °C or
-31 °F (measurement displayed “****”)
v RTD disconnection is detected if the measured temperature is greater than
+205 °C or +401 °F (measurement displayed “-****”).
If an RTD fault is detected, the set point output relays are inhibited: the protection
outputs are set to zero.
The "RTD fault" item is also made available in the control matrix and an alarm
message is generated.
Block diagram
RTD
T < +205 ˚C
T > -35 ˚C
Characteristics
&
&
T > Ts1
T > Ts2
set point 1
set point 2
RTD’s fault
Ts1 and Ts2 set points °C °F
Setting 0 °C to 180 °C 32 °F to 356 °F
Accuracy (1) ±1.5 °C ±2.7 °F
Resolution 1 °C 1 °F
Pick-up/drop-out difference 3 °C ±0.5 °
Characteristic times
Operation time < 5 seconds
(1) See "connection of MET148-2 module" chapter for accuracy derating according to wiring
cross-section.
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