IMM 8001/8002 – Digital Motor Protection Relay
ICE / CEE
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IMU307-1 GB Ind. B
46
5.5 START AUTHORISATION FUNCTION [5]
Function
Motor start authorisation or inhibit is given by means of a relay contact (relay P is recommended for this
use). When motor start is authorised, the output unit is not energised ; when motor start is inhibited, it is
energised. To perform this function, the relay checks :
The motor thermal state : [5/49]
The user can adjust a thermal operating level
θ
d> above which start authorisation is disabled. This
operating level has the following characteristics :
Adjustment
θ
dm>
40 – 100 %
θ
n in steps of 1 %
θ
n
When the operating level is reached, motor start is inhibited.
To allow another start, the thermal state
must have returned below the operating level (fixed return difference equal to 6 %).
Too frequent starts : [5/66]
The user sets parameters for the number N of allowed starts during a given period t. If the number N is
reached during a period t, then any new attempted start is inhibited during time T.
N : maximum number of starts
1 - 8 starts in steps of 1
t : authorisation period for N starts
15-60 minutes in steps of 1 min.
T : inhibit period for another start
15-60 minutes in steps of 1 min.
Voltage range : [5/27 + 59]
If the supply voltage of the motor is not within an operational range, the start is inhibited. The user sets
parameters for the under and over voltage operating level values, as well as for the time after which the
authorisation is given (
NB
: use of this authorisation presupposes that the PT supplying the protection is
upstream of
the switching device).
-
Operating level U<
20 - 120 % Un in steps of 1 % Un
-
Operating level U>
70 - 150 % Un in steps of 1 % Un
-
authorisation time-delay tU</>
0.5 - 100 s in steps of 0.1 s
(after allowed range entry)
-
inhibit control order
instantaneous (about 0.3 s)