14/1/98 Page 13 Issue H
7.3 Setting procedure
In the following sections the setting of all relay parameters is described in detail:
7.3.1. t6x Setting
This setting specifies the time the relay will take to trip at 6 times FLC, with respect to the cold
characteristic curve, and therefore determines the basic thermal characteristic.
7.3.2. Speed Switch
When this function is enabled (see speed switch matrix, Snnn) the relay operation times are
decreased as a function of the percentage setting selected, if the motor becomes stalled when starting
or running. The speed switch should be connected such that when the speed falls (stall situation) a
switch opens and disconnects an auxiliary voltage at the terminals shown in Figs 1 and 2. This is
regarded as a fail safe connection. The auxiliary voltage can be the same as the relay power supply
or any other source within the same range.
7.3.2.1. A Starting Stall
Note that the action of the speed switch is ignored for the first period of a start determined by half the
t6x setting in seconds. After this, should a starting stall develop, the remainder of the trip time is
carried out at a reduced time according to the setting of the Snnn matrix. The actual total trip time t
ss
for a stall during starting for which the normal trip time would be t
cold
is given by:
Where t6x=Relay Setting
S=25%, 50% or 75% according to the matrix Snnn.
7.3.2.2. A Running Stall
If the motor has started normally, has been running and then develops a stall, the trip time t
rs
is given
by
Where t
hot
is the normal hot curve trip time.
7.3.3. Full Load Current Setting I FLC
Note that the CT primary setting(see below) MUST BE SET FIRST.
This setting corresponds to the normal running full load current of the machine, set in primary
amps. This setting is limited to the range 0.5 - 1. 25 x CT rating.
7.3.4. CT Primary Setting
This setting, should be set equal to the line CT rating in primary amps.
1002
6
2
6 S
x
xt
t
xt
t
coldss
−+=
S
xtt
hotrs
=
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