2. Motor Data : MEG Col.
Reboiler Recirculation Pump-A/B
(42-PM-624A/B)
Relay type / Manufacturer : 7SJ612/ SIEMENS
Relay function : MPR (48, 49, 66, 51M, 50, 50N, 46)
Phase fault current : 41.4 kA
Earth Fault Current : 39.9 kA
Capacity : 110kW
Voltage : 0.415 kV
Full load current : 183A
Starting Current : 1006.5 A
Starting time at 75% V (sec) :2
Starting time at 100% V (sec) :1
Locked motor withstand time
(cold/hot) sec. at 75% V (sec) : 40.8/20.4
Locked motor withstand time
(cold/hot) sec. at 100% V (sec) : 24/12
CT ratio : 300/5A
MPR (48, 49, 66, 51M, 50, 50N, 46) setting
A. Motor Starting Protection (48)
Istart @ 85%
i) Startup Current :
CT ratio
(Min Voltage available at start is 85%)
1006.5 0.85 5
: 300
Recommended setting (4102) : 14.3 A
ii) Startup Time
This setting should lie above the starting time at normal startup current. The starting
time at 100% voltage is 1 sec.
Recommended setting (4103) : 2.5 sec
iii)Locked Rotor Time
Locked rotor time should be less than or equal to Thermal withstand (hot) at 100% V.
Recommended setting (4104) : 11 sec
iv) Startup T warm
This setting should lie above max starting time and below thermal withstand time at
100% V.
Recommended setting (4105) : 2.5 sec
v) Temp. Cold Motor
It is derived from the number of cold (n cold) and warm (n warm) motor startups.
(n cold) - (n warm)
limit : 100%
n cold
2 -1
: 100%
2
: 50%
The setting should be set below the limit value, considering safety margin.
Recommended setting (4106) : 25%
B. Thermal Overload Protection (49)
The overload protection prevents thermal overloading of the motors stator winding.
Ifl
i) Overload parameter, K-Factor :
Ict
183
: 300
: 0.61
Recommended setting (4202) : 0.61
ii) Time Constant
From motor thermal withstand characteristic curves (please refer TCC curve), a setting of
6.5 min time constant achieves the relay characteristics lie below the
motor hot characteristic.
Recommended setting (4203) : 6.5 min
iii)Thermal Alarm Stage (49 Alarm)
Thermal warning stage offers an additional warning stage before the tripping temperature
is reached. This is why it should be set to below the 100% tripping threshold, for example
90%.
With max permissible current of 1.1, over loading temperature rise limit value is, 1/k2
: 1/ (1.1 X 1.1)
: 83%
of the tripping temperature. A setting value of 90% therefore lies above the operationally
expected over temperature of 83%, but below the tripping temperature of 100%.
Recommended setting (4204) : 90%
iv) Current Alarm Stage (I Alarm)
A current alarm stage can be set in addition to thermal alarm stage. This can be set
equal to the continuously permissible secondary rated current.
183 5
: 300
: 3.05
Recommended setting (4205) : 3.05 A
v) K - Factor
The machines cool down behavior at standstill can be taken into account with the K
Factor.
The default setting is 1.
Recommended setting (4207A) :1
vi) T Emergency
Recommended setting (4208A) : 100 sec
vii) 49 Temperature rise I
Recommended setting (4209) : 100°C
C. Motor Restart Inhibit (66)
The motor restart inhibit prevents restarting of the motor when this restart may cause the
permissible thermal limits of the rotor to be exceeded.
i) Starting Current / Motor Current (I start /I Mot. nom )I
start / I Mot. nom
1006.5
: 183
: 5.5
Recommended setting (4302) : 5.5
ii) Maximum Permissible Starting time ( T start max)
Recommended setting (4303) : 2.5 sec
iii) Rotor Temperature equalization time (T equal)
It defines the minimum dead time between individual starts. The default setting is 1
min.
Recommended setting (4304) : 1 min
iv) Rated Motor Current (I motor Nominal)
This can be set equal to the continuously permissible secondary rated current.
183 5
: 300
: 3.05
Recommended setting (4305) : 3.05 A
v) Max. Warm Starts
Max. No. of warm starts 2
Recommended setting (4306) 2
vi) #Cold-#Warm
This can be set equal to difference between allowed no. of cold and hot starts.
Recommended setting (4307) 1
vii) K at Stop
Extension factor for the time constant during cool down
K at Stop
Cooling Time Constant
: Heating Time
Constant
Recommended setting (4308) 5
viii) K at Running
This setting is shorter than K at stop because rotor operation involves intrinsic cooling.
Recommended setting (4309) 2
ix) Min restart inhibit time, T Min inhibit:
Recommended setting (4310) : 6 min
D. Load Jam Protection (51M)
i) Load Jam Current (I>)
: 2 Ifl
2 183 5
: 300
: 6.1 A
Recommended setting (4402) : 6.1 A
ii) Trip Delay
The default setting is 1 sec.
Recommended setting (4403) : 1 sec
iii)Alarm current (I Alarm)
: 90% of 2Ifl
: 0.9 6.1
: 5.5 A
Recommended setting (4404) : 5.5 A
iv) Alarm Delay
The default setting is 1 sec.
Recommended setting (4405) : 1 sec
v) Start Block Time (T Start BLK)
This value shall be equal to address code 4103.
Recommended setting (4406) : 2.5 sec
E. Short Circuit Protection (50)
Pickup Current
Disabled, since symmetrical fault will be cleared by fuse.
Recommended setting (1204) : Disabled
ii) Delay
Recommended setting (1205) : Disabled
F. Earth fault Protection (50N)
i) Pickup Current
: 10 % x ICT. Sec
: 0.1 5
Recommended setting (1304) : 0.5 A
ii) Delay
Recommended setting (1305) : 2 sec
G. Negative Sequence Protection (46)
This function is set in two stages. The first stage 46-1 is set for alarm, while 46-2 is set
for trip. Alarm is initialized when the negative sequence current exceeds 20% of full
load current for specified time delay.
i) 46-1 Pickup
: 20 % x IFLC
0.2 183 5
:
300
: 0.6 A
Recommended setting (4002) : 0.6 A
ii) Delay
Recommended setting (4003) : 1.5 sec
Tripping element 46-2 is set to pickup at 40% of the rated current with comparatively
shorter time delay of 0.5 sec.
iii) 46-2 Pickup
: 40 % x IFLC
0.4 183 5
:
300
: 1.2 A
Recommended setting (4004) : 1.2 A
iv) Delay
Recommended setting (4005) : 0.5 sec
