3
The microprocessor based motor protection
relay SPAM 150 C is an integrated design
current measuring multifunction relay for the
complete protection of a.c. motors. The main
area of application covers large or medium-sized
three-phase motors in all types of conventional
contactor or circuit breaker controlled motor
drives. The motor protection relay is available in
two versions, one with a making trip contact and
the other with a breaking trip contact.
The relay can also be used in other applications
requiring a single-, two- or three-phase over-
current and/or overload protection and non-
directional earth-fault protection.
Area of
application
The combined multifunction motor protection
relay is a secondary relay device which is con-
nected to the current transformers of the pro-
tected motor drive. The three phase currents
and the neutral current of the protected device
are continuously measured and on the basis of
this measurement, the thermal condition of the
motor is calculated and the faults of the network
are detected. In fault situations the protective
units of the relay provide alarm or trip the
circuit-breaker.
By appropriate programming of the output re-
lay matrix, various starting, prior alarm or re-
start inhibit signals are received as contact
functions. This contact information is used e.g.
for the blocking of co-operating protective re-
lays located upstreams, for connection to annun-
ciator units etc.
The motor protection relay contains one exter-
nal logic control input, which is activated by a
control signal on the auxiliary voltage level. The
influence of the control input on the relay is
determined by programming switches of the
measuring module. The control input can be
used either for blocking one or more of the
protective stages, for carrying out an external
trip order, for inhibiting a restart attempt or for
resetting a latched output relay in the manual
reset mode.
Short description
of operation
Fig. 1. Protective functions of the motor protection relay type SPAM 150 C.
The encircled numbers refer to the ANSI-numbering of protective functions.
START
THREE-PHASE THERMAL
OVERLOAD PROTECTION
TRIP
SIGNAL 1
SERIAL PORT
IL1
IL2
IL3
Io
PRIOR ALARM
OR SIGNAL 2
IRF SELF-SUPERV.
CONTROL
INPUT BS
CUMULATIVE START-UP
COUNTER AND RESTART
INHIBIT FUNCTION
SERIAL COMMUNICATION PORT
STALL PROTECTION WITH
SPEED SWITCH INPUT FOR
DRIVES WHERE ts > te
LOW-SET DEFINITE TIME
EARTH-FAULT PROTECTION
RESTART
ENABLE
DEFINITE TIME UNDER-
CURRENT PROTECTION
49
51N
37
46
INCORRECT PHASE SEQUENCE
AND PHASE INVERSE TIME
UNBALANCE PROTECTION
51
THERMAL STRESS SUPERVISION
ALT. THREE-PHASE DEFINITE TIME
OVERCURRENT PROTECTION
14
THREE-PHASE HIGH-SET
DEFINITE TIME OVERCURRENT
PROTECTION
50
48
