Areva MiCOM P225, Техническое руководство

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P225/EN FT/B11 User Guide
Page 22/52 MiCOM P225
4.10.1.3 Thermal alarm function:
θ
ALARM
The purpose of this function is to produce an alarm signal indicating that the thermal state
θ
of the motor has exceeded an adjustable threshold: ALARM. Corrective action can thus be
taken before thermal tripping occurs.
Once the threshold
θ
ALARM is exceeded, the MiCOM P225 relay calculates and displays,
in the PROCESS menu (cf. chapter 4.7 The PROCESS menu), an estimate of the time
remaining before a thermal trip THERM. OV. occurs. This estimate is given for a constant
overload rate.
4.10.1.4 Thermal base blocking start function:
θ
FORBID. START
This function makes it possible to block a start on a hot motor, or not, as a function of its
thermal state. When this function has been adjusted in service by the user, a further start is
inhibited for the motor as long as its thermal state
θ
is higher than an adjustable threshold
θ
FORBID START. It is then necessary to wait until the motor cools down. When the value of
the thermal state
θ
falls below the threshold
θ
FORBID START, the starting of the motor is
authorised.
The blocking start
θ
FORBID START information is activated if both of the 2 following
conditions are met:
−
Motor shut down: logic input L1 in the zero state (terminals 22-24).
−
Thermal state value
θ
higher than the threshold
θ
FORBID START.
The following diagram illustrates the operation of the thermal base blocking start criterion:
Thermal state
θ
of
the motor
Time
FORBID START
threshold
Shutdown of
the motor
Restarting of the
motor
θ
FORBID START signal
Binary input L1 : interlock o/o (52A)
P0191ENa