Sepam series 20 Sepam series 40 - POWERLAB

Protection
Description
Directional power protection
functions
ANSI 32P - Directional active overpower
This protection function is activated if the power flowing
in one direction or the other, according to the
application (supplied or absorbed), is greater than the
set point.
ANSI 32Q/40 - Directional reactive overpower
This protection function may be used to detect
synchronous machine (generator or motor) field loss.
The protection function is activated if the reactive
power flowing in one direction or the other, according to
the application (supplied or absorbed), is greater than
the set point.
Machine protection functions
ANSI 49RMS - Thermal overload
Protection of equipment against thermal damage caused by overloads.
The protection may be inhibited by a logic input when required by process control
conditions.
The thermal capacity used is calculated according to a mathematical model which
takes into account:
b current RMS values
b ambient temperature
b negative sequence current, a cause of motor rotor temperature rise.
The protection function comprises 2 groups of settings, each of which includes:
b an adjustable alarm set point
b an adjustable trip set point
b the initial thermal capacity used setting, in order to accurately adapt the protection
characteristics to fit the equipment’s thermal withstand curves supplied by the
manufacturer.
b the equipment’s heating and cooling time constants.
Sepam series 40 has a function that automatically calculates the cooling time
constant based on measurement of the equipment temperature by a sensor.
Application for a transformer:
switching of groups of settings by a logic input according to the transformer
ventilation operating rate, natural or forced (ONAN or ONAF).
Application for a motor:
switching of groups of settings according to a current set point to take into account
the thermal withstand of the motor with a blocked rotor.
ANSI 37 - Phase undercurrent
Protection of pumps against the consequences of loss of priming.
The protection function detects time-delayed current drops that correspond to motor
no-load operation, characteristic of the loss of pump priming.
ANSI 48/51LR/14 - Locked rotor / excessive starting time
Protection of motors that are liable to start with overloads or insufficient supply
voltage and/or that drive loads that are liable to jam (e.g. crushers).
The locked rotor function is an overcurrent protection function that is only confirmed
after a time delay that corresponds to the normal starting time.
Motor reacceleration and locked rotor detection (detection of zero speed) may be
taken into account by logic inputs.
ANSI 66 - Starts per hour
Protection against overheating caused by too frequent starts.
Checking of the number of:
b starts per hour (or adjustable time period)
b consecutive starts.
The protection inhibits motor energizing for a preset time period once the permissible
limits have been reached.
Motor re-acceleration may be taken into account by a logic input.
ANSI 26/63 - Thermostat, Buchholz, gas, pressure, temperature detection
Protection of transformers against temperature rise and internal faults via logic inputs
linked to devices integrated in the equipment.
ANSI 38/49T - Temperature monitoring by RTD
Protection function that detects abnormal overheating of the windings and/or
bearings of motors equipped with RTDs.
The protection includes 2 independent set points that are adjustable for each RTD.
ANSI 27D - Positive sequence undervoltage
Protection of motors against faulty operation due to insufficient or unbalanced supply
voltage and detection of reverse rotation direction.
In order for the protection to be used, voltage transformers must be connected to
Sepam to measure U21 and U32.
ANSI 27R - Remanent undervoltage
Monitoring of the clearing of voltage sustained by rotating machines after circuit
opening. The protection is used to prevent transient electrical and mechanical
phenomena that are caused by fast re-energizing of motors.
It monitors phase-to-phase voltage U21 or phase-to-neutral voltage V1.
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