ABB FM9925A-E HIEE451116R0001 programmable control detection module
The feeder protection relay is provided with
six energizing inputs for phase currents and
inputs for residual or neutral currents. The
relay is also equipped with nine output relays
for CB control, signalling, etc.
The differential relay consists of three protec tion relay modules, i.e. a differential relay
module, an earth-fault relay module and a
combined overcurrent and earth-fault relay
module. The modules are withdrawable as are
the power supply module and the I/O relay
module located behind the system front
panel.
Differential relay module
SPCD 3D53
The differential relay module includes three
protection units, i.e. a stabilized differential
current unit, an instantaneous differential cur rent unit and a circuit-breaker failure protec tion unit. In addition, the module contains a
disturbance recorder unit.
The stabilized differential current unit consti tutes the main differential protection. The
unit is provided with second and third har monic restraint, selectable transformer vector
group, zero-sequence current elimination,
numerical correction of CT ratios and flexible
configuration of tripping, blocking and con trol signals.
The instantaneous, non-stabilized differential
current unit functions as an ultra-fast protec tion unit with an operate time less than 30 ms
at heavy faults.
The circuit-breaker failure protection unit is
activated by the main trip signal of the other
protection units and it provides a second trip
signal to be routed to a back-up circuit
breaker if the main CB fails to operate.
The differential relay module also incorpo rates a digital disturbance recorder module.
The module continuously monitors the object
protected and stores pre- and post-fault net work information, which can be used for
post-fault analysis.
Earth-fault relay module
SPCD 2D55
The earth-fault relay module measures the
neutral current and/or residual current on both
sides of the object protected. The earth-fault
protection can be implemented by four differ

ent principles, i.e. the high-impedance principle, the numerical stabilized differential
current principle, the residual overcurrent
principle or the neutral overcurrent principle.
Both sides of the object can be protected
independent of each other, which means that
the protection principle on one side does not
have to be the same as that of the other side.
The circuit-breaker failure protection unit is
activated by the main trip signal of the protection units and it provides a second trip signal to be routed to a back-up circuit breaker if
the main CB fails to operate.
The earth-fault relay module also incorporates a digital disturbance recorder module.
The module continuously monitors the object
protected and stores pre- and post-fault network information, which can be used for
post-fault analysis.
Combined overcurrent and
earth-fault relay module
SPCJ 4D28
The combined overcurrent and earth-fault
module includes four protection units, i.e. an
overcurrent unit, an earth-fault unit, a phase
discontinuity unit and a circuit-breaker failure
protection unit.
The three-phase overcurrent unit comprises
three overcurrent stages, i.e. a low-set stage
I>, a high-set stage I>> and a super high-set
stage I>>>. The low-set stage can be given
definite time characteristic or inverse time
characteristic while the high-set stage and the
super high-set stage have a definite time characteristic.
The non-directional earth-fault unit comprises two protection stages, i.e. a low-set
stage I0> and a high-set stage I0>>. The lowset stage can be given definite time characteristic or inverse time characteristic while the
high-set stage has a definite time characteristic.
The phase discontinuity protection unit measures the phase unbalance and has a definite
time characteristic.
The circuit-breaker failure protection unit is
activated by the main trip signal of the protection units and it provides a second trip signal to be routed to a back-up circuit breaker if
the main CB fails to operate.