Siemens siprotec SJ62 User Manual page 184

Ambient or Coolant
Temperature
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
The indications specified up to now are sufficient for a temperature rise replica. The
ambient or coolant temperature, however, can also be processed. This has to be com-
municated to the device as digitalized measured value via the interface. During con-
figuration the parameter 142 49 must be set to With amb. temp..
If the ambient temperature detection is used, the user must be aware that the 49 K-
FACTOR to be set refers to an ambient temperature of 104° F or 40° C, i.e. it corre-
sponds to the maximum permissible current at a temperature of 104° F or 40° C.
All calculations are performed with standardized quantities. The ambient temperature
must also be standardized. The temperature with nominal current is used as standard-
ized quantity. If the nominal current deviates from the nominal CT current, the temper-
ature must be adapted according to the following formula. In address 4209 or 4210
49 TEMP. RISE I the temperature adapted to the nominal transformer current is
set. This setting value is used as standardization quantity of the ambient temperature
input.
with
Θ
Nom sec
Θ
Nom mach
I
Nom CT prim
I
Nom mach
If the temperature input is used, the trip times change if the coolant temperature devi-
ates from the internal reference temperature of 104° F or 40° C. The following formula
can be used to calculate the trip time:
with
τ
th
k
I
Nom
I
I
Pre
Θ
Ut=0
Θ
Nom
Θ
u
2.10 Thermal Overload Protection 49
Machine temperature with secondary nominal current
= setting at the protective relay (address 4209 or
4210)
Machine temperature with nominal machine current
Nominal Primary CT Current
Nominal Current of the Machine
TIME CONSTANT (address 4203)
49 K-FACTOR (address 4202)
Nominal device current in A
Fault current through phase in A
Previous load current
Coolant temperature input in °C with t=0
Temperature with Nominal Current I
49 TEMP. RISE I)
Coolant temperature input (scaling with address 4209
or 4210)
(Address 4209
Nom
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