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Emergency
Starting
Ambient or Coolant
Temperature
7UM62 Manual
C53000-G1176-C149-3
despite increasing current values. The limit value must be specified at a value
ensuring that, even for the highest possible short-circuit current, the trip times of the
overload protection exceed the trip times of the short-circuit protective relays
(differential protection, impedance protection, time overcurrent protection). As a rule,
this parameter can be set to three times the nominal generator current.
The run-on time to be entered at address 1616A T EMERGENCY must be sufficient to
ensure that after an emergency startup and dropout of binary input >Emer.Start O/
L" the trip command is blocked until the thermal replica is again below the dropout
threshold.
The indications specified up to now are sufficient for the modeling of the
overtemperature. In addition to this, the machine protection can also process the
ambient or coolant temperature. This temperature value can be fed to the relay via
measuring transducer TD2 as a temperature-proportional DC current from a
measuring transducer with a live zero signal between 4 and 20 mA, or communicated
to the relay as digitalized measuring via the Fieldbus. Address 1607 TEMP. INPUT
serves to select the temperature input procedure. If there is no coolant temperature
detection, the address1607 is set to Disabled. The assignment between the input
signal and the temperature can be set at address 1608 (in °C) or 1609 (in °F) TEMP.
SCAL.. The value set there is equivalent to 100 % of the Profibus DP/Modbus value,
or full-scale deflection (20 mA) of the measuring transducer. In the default setting,
100 % (Profibus DP/Modbus) or 20 mA (measuring transducer TD2) correspond to
100 °C.
Is under address 1607 TEMP. INPUT the setting temperature of RTD 1 selected, the
temperature scaling of addresses 1608, 1609 is ineffective. Neither of the
parameters is considered in the calculation.
If the ambient temperature detection is used, the user must be aware that the K-
FACTOR to be set refers to an ambient temperature of 40 °C, i.e. it corresponds to the
maximum permissible current at a temperature of 40 °C.
All calculations are performed with standardized quantities. The ambient temperature
must also be standardized. The temperature with the nominal machine current is used
as standardization quantity. If the nominal machine current deviates from the nominal
primary CT current, the temperature must be adapted according to the following
formula. At address 1605 or 1606 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.
where Θ
– Machine temperature with nominal secondary current = setting at
Nsec
the 7UM62 (address 1605 or 1606)
Θ
– Machine temperature with nominal machine current
NMach
I
– Nominal primary current of the current transformers
Nprim
I
– Nominal machine current
NMach
If the temperature input is not used, the address 1607 TEMP. INPUT must be set to
Disabled. In this case, the settings of the addresses1605 or 1606 and 1608 or
1609 are not considered.
Thermal Overload Protection (ANSI 49)
I
æ
Nprim
Θ
Θ
⋅
----------------- -
=
è
Nsec
NMach
I
NMach
2
ö
ø
61
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