5
Increasing the
sensitivity of the
earth-fault protection
The sensitivity of the operation of the earth-fault
protection can be increased by using the 1 A in-
put instead of the 5 A input. This is possible in a
solidly earthed network too, because the thermal
withstand is normally high enough when using a
tripping earth-fault protection.
Optimizing the
needed time left
to restart
The approximate time until a restart is allowed
can be read out from register 9 on the measur-
ing module. Also note that this value is updated
even when the motor is in service. For a motor
with a long cooling time this can give valuable
information on how to cool down the motor
before shutdown in order to reduce the needed
downtime before restart. If possible, the motor
is allowed to run with a minimum load thus
that the register showing necessary time to re-
start has been reduced to a suitable value. An
idling time of e.g. 15 minutes can save an hour
in cooling at standstill.
Time constant versus
safe stall time t
6x
If the thermal unit is to be set according to the
single time constant of an object the time con-
stant can be calculated as:
τ
= 32 x t
6x
.
This is
correct provided that the factor p is set at 100%.
External trip via
control input
If an added function is needed, e.g. under-
voltage, RTD-trip or a similar, an external re-
lay can be linked to trip via the control input
(SGB/5 = 1). The benefits are that the exter-
nal relay can have a light duty output relay be-
cause the trip is carried out by the SPAM.
Furthermore all event and memorized infor-
mation from the trip instant can be achieved
from the SPAM 150 C also over the commu-
nication link.
Disabling of restart
inhibit for use outside
SPAM 150 C
A switch SG4/2 can be used to lock out the re-
start enable signal when the module SPCJ 4D34
is used in other packages than SPAM 150 C. This
might often be necessary as the restart enable sig-
nal can otherwise interfere with a trip output.
The switch is found in submenu position 4 in
the register "A" and is normally = 0 but should
bet set = 1 to disable the restart inhibit signal.
Mutual restart
inhibit for multi-
motor applications
If a number of large motors are run in a weak
network, a simultaneous start of two or more
motors may cause complete network break-
down. Under these circumstances a restart in-
hibit logic is needed and the easiest way to ob-
tain such an arrangement is to link the start-up
information from each motor relay to the ex-
ternal control input of all the other relays and
to program the inputs to operate as restart in-
hibit inputs. In this way the start-up of one
motor always prevents a simultaneous start of
any one of the other motors.
Note about the
contactor versus
circuit-breaker drives
Different output relay cards needed for contac-
tor versus circuit breaker controlled drives:
Power and output relay modules type SPTU 240
R2 and SPTU 48 R2 comprise normally open
trip contacts for circuit breaker operation where-
as modules SPTU 240 R3 and SPTU 48 R3
have a normally closed trip contact for contac-
tor controlled drive use. When ordering the re-
lay, this power module type as well as the relay
rated frequency are indicated by the RS-number
of the relay.
The actual RS-numbers for SPAM 150 C are:
For circuit-breaker drive applications:
RS 641 014 - AA ;50 Hz, 80...265 V ac/dc
RS 641 014 - CA ;50 Hz, 18...80 V dc
RS 641 014 - DA ;60 Hz, 80...265 V ac/dc
RS 641 014 - FA ;60 Hz, 18...80 Vdc
For contactor drive applications:
RS 641 015 - AB ;50 Hz, 80...265 V ac/dc
RS 641 015 - CB ;50 Hz, 18...80 V dc
RS 641 015 - DB ;60 Hz, 80...265 V ac/dc
RS 641 015 - FA ;60 Hz, 18...80 Vdc
Summary of Contents for SPAM 150 C
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