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1MDU07212-YN Rev. D
REF601 / REJ601 / REM601
Application Manual
Thermal characteristic warming condition at diabatic behavior:
2
��
��
= ��
+ ((
)
− ��
) ∗ (1 − ��
1
0
0
��
��
ϑ
= new value of thermal image
1
ϑ
= present value of thermal image
0
I = maximum value of measured phase currents
I
= base current (rated current/full load current defined by setting).
b
Δt = time interval between ϑ
τ↑ = Heating time constant
Thermal characteristic warming condition at adiabatic behavior:
2
��
∆��
��
= ��
+ (
)
∗ (
)
1
0
��
��
��
↑
The value of ϑ
IED is defined by a setting
2. Constant thermal image of protected object:
During this condition, the dissipated heat is equal to heat generated by the current
flowing through the protected object.
The thermal model for this conditions is as follow:
��
= ��
1
0
whereas:
2
��
∗ 100 [ % ]
��
= (
)
0
��
��
ϑ
= new value of thermal image
1
ϑ
= present value of thermal image
0
I = maximum value of measured phase currents
I
= base current (rated current/full load current defined by setting).
b
3. Cooling of protected object:
When the current reduces compared to previous condition or the motor has stopped
it results into cooling of an apparatus.
Cooling condition is defined when:
2
��
∗ 100 [ % ]
��
> (
)
0
��
��
The thermal model used during cooling condition for standing objects (cable /
transformer / standing motor) is:
2
��
��
��
= (
)
+ (��
− (
1
0
��
��
��
��
Protection and Control Function
∆��
−(
)
)
��↑
and ϑ
0
1
at the start of the function (i.e. at power on of the
0
∆��
2
−(
)
)
) ∗ ��
�� ↓��
Section 4
27
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