Section 4 1MDU07212-YN Rev. D
Protection and Control Function
28 REF601 / REJ601 / REM601
Application Manual
The thermal model used during cooling condition for rotating machines is:
ϑ
1
= new value of thermal image
ϑ
0
= present value of thermal image
I = maximum value of measured phase currents
I
b
= base current (rated current/full load current defined by setting).
Δt = time interval between ϑ
0
and ϑ
1
τ
↓s
= Cooling time constant of standing objects
τ
↓r
= Cooling time constant of rotating objects (only REM601)
Emergency start function for motors:
An additionally configurable start emergency input (START_EMERG) is
provided. When the activated, the emergency mode is activated, which temporary
increase the thermal trip value ϑ
trip
by the setting ϑ
EM
in %. For function to remain
in emergency mode, it is required that START_EMERG remains active
continuously. As soon as the input is deactivated, trip value will restore back to
original setting. The activation and deactivation of input START_EMERG is
recorded as an event.
Block closing of CB
To prevent overheating of hotspots within a motor during startup, the restart could
be blocked if the actual thermal image is above by the setting of ϑ
startinhibit
. During
this condition the output to block closing of the CB (BLK_CLOSE) is activated.
When BLK_CLOSE is active closing of CB is not allowed by any means (i.e.
communication or HMI or binary input). The activation and deactivation of
BLK_CLOSE will be recorded as an event.
The thermal value of at the start of the function (i.e. at power on
of the IED is defined by a setting
Behavior of thermal image during power down condition of IED:
Condition arises where in the power supplied to the IED is interrupted. The user
could select four different behaviors / options to calculate the thermal level when
the power is restored. These options are selectable by the setting Mode ϑ
powerOFF
.
The thermal image along with time is stored every 60 sec. (and for option 1 also
the actual maximum phase current).
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