Description
The Power Management System and the Alternator
Protection System will not be delivered within the
scope of MAN Diesel & Turbo.
But in order to advise and give our customers the
best possible background to make some investiga-
tions regarding their Power Management System /
Alternator Protection System MAN Diesel & Turbo
will in the following give some guidelines and rec-
ommendations.
It is only our recommendation and it is the custom-
er’s responsibility to specify source and to set the
different protection values together with the PMS
system maker.
The customer must be aware that local regulations
and requirements from authorities must also be
taken into considerations during thespecification
and design phase of these systems.
Overcurrent protection Node
ANSI – Code: 50+51
Application: Two stage. Overcurrent/ time and short
Circuit/time. It shall be an independent time over-
current relay, with inverse overcurrent time adjust-
ments, with selectable characteristics, and determi-
nation of fault direction.
Function: Protecting generator, mains decoupling,
Radial feeder, Overhead lines and cables by tripping
the generator circuit breaker.
Thermal overload
ANSI-Code:49
Protection of thermal damage caused by overload .
The thermal capacity used is calculated according
to a model, which takes into account:
Current RMS values, ambient temperature, negative
sequence current.
AC voltage protection
ANSI-Code: 27+59
Application : Voltage supervision of 1-phase og 3 –
phase systems, two stage over- and under voltage
protection of the alternator against abnormally low
net voltage, which trigger load transfer in to the
machine.
It is protecting of the generator against abnormally
high net voltage, works with phase to phase and
phase to neutral voltage, each voltage is monitored
separately. Min volt. 95%, max volt 105%, volt to
ground 5% 200msec.
Function: Protecting generator, mains decoupling,
Radial feeder, Overhead lines, and cables by trip-
ping the alternator circuit breaker.
Earth fault current protection
ANSI-Code: 50+51N
Application: Independent time over current relay,
inverse overcurrent with selectable characteristic.
The directional earth fault determination is based on
the active and the reactive current flow and the zero
sequence system.
Insulated or compensated as solid state earthed/
resistance-earth, neutral point systems, is the crite-
rion for earth fault detection depending on the neu-
tral point connection method.
Function : Protecting generator, by tripping the
alternator circuit breaker.
Mains decoupling (vector surge)
ANSI-code: 78
Application: The mains decoupling relay is protect-
ing parallel running generators against short time
voltage interruptions. Whit this it is possible to get a
protection against damaging asynchronous syn-
chronisation. An interruption of 300 msec is damag-
ing.
Function : Protecting generator, by tripping the
alternator circuit breaker.
Frequency protection
ANSI-code: 81
Application: Frequency protection is protecting the
alternator and consumers against over and under
frequency continuous and fluctuating.
Function: Protecting generator, by tripping the alter-
nator circuit breaker.
Directional power protection
ANSI-code: 32
MAN Diesel & Turbo
3700383-8.2
Page 1 (6)
Power Management - Alternator protection
B 17 00 0
L23/30DF, L28/32DF, V28/32S, L28/32S, L28/32H, L27/38S, L27/38, L23/30S,
L23/30H, L21/31S, L21/31, L16/24S, L16/24
2015.11.17
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