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NVA100X-D - Manual - 02 - 2016
FUNCTION CHARACTERISTICS
Cold Load Pickup - CLP for motor-generator protection
Preface
CLP feature allows selected thresholds to be changed or blocked for an adjustable time in order to
overcome transient overcurrents.
If the CLP (Cold Load Pick-up) function is set for threshold blocking the selected element is blocked
for an adjustable time according the selected mode for the control of starting (starting from closure
of the circuit breaker or based on the IRUN threshold)
[1]
.
If the CLP (Cold Load Pick-up) function is set for setting changes the selected element is blocked
for an adjustable time according the selected mode for the control of starting (starting from closure
of the circuit breaker or based on the IRUN threshold)
[1]
.
The operating mode, the CLP activation time and the threshold value within the CLP are available
inside the menu of the elements where the CLP function are available
At the end of the CLP count the threshold is unblocked if CLP is set to ON threshold block or the
threshold is revert back to the original value if CLP is set to ON threshold change.
Starting control
With IRUN setting of the CLP Source parameter and the highest value among the three phase cur-
rents is less than 0.1 I
B
, the protection is blocked or the threshold is changed depending on the setting
of parameters I2CLP> Mode, I2CLP>> Mode, DthCLP Mode, ICLP>Mode, ICLP>>Mode,
ICLP>>>Mode, IECLP>Mode, IECLP>>, Mode IECLP>>>Mode, IEDCLP>Mode,
IEDCLP>>Mode, IEDCLP>>>Mode, IEDCLP>>>>Mode.
With CB setting of the CLP Source parameter, and the CB is open, the protection is blocked or the
threshold is adjusted depending on the setting of these parameters.
The function requires information on the state of the Circuit Breaker that can be acquired through
logic inputs connected to the auxiliary contacts 52b and 52b.
When the closed CB condition is detected the CLP timer starts and within the counting the element
is blocked or switched to an higher adjusted value.
At the end of the CLP count the lock is removed or the threshold value is switched back to normal.
Note that when the circuit breaker is open, the threshold is already blocked if CLP is set to ON
threshold block or the threshold is already changed to the value if CLP is set to ON threshold change:
this is useful in order to avoid unwanted tripping due to unblocked threshold or threshold with his
original value for cases where a delay of the circuit breaker closing happen, i.e. where the three
poles of the CB do not close at the same time or during long CB closing time.
If CLP is enabled in blocking mode of one or more thresholds, the corresponding threshold is blocked
for an adjustable time, counted from closing of the CB.
If CLP is enabled in change setting of one or more thresholds, the corresponding threshold can be
changed to an adjustable time, counted from closing of the CB.
The CLP Source, parameter, available inside the Set \ Starting control set menu is common for the
A and B profi les.
Re-acceleration
In a re-acceleration phase a current value close to locked rotor is absorbed by the motor but with-
out the current has previously cleared or dropped below the IRUN = 0.1 IB value; in this condition,
the CLP function is inactive so unwanted trip may arise. If a binary input is assigned to the “Motor
restart” function and inside the “Starting control set” menu the reset of the timing of all the CLP
thresholds (MR Enable ON)
[2]
is enabled, the timer counting is restarted so that the thresholds are
changed or blocked for the time set in order to avoid unwanted tripping.
Operation and settings
For each threshold the CLP function may be disabled (OFF), enabled with threshold blocking (ON-
Element blocking) or enabled with threshold change (ON-Change setting) by means the xx-
CLPx Mode parameter.
The operating mode and the relative activation time concerning each threshold of the 46, 49,
50/51, 50N/51N and 67N/67N elements are adjustable inside the Set \ Profi le A(or B)\ xxx - xx
\ xxx Element \ Setpoints menus.
Example: to change the fi rst threshold of the defi nite time overcurrent element 50/51 within CLP dur-
ing a 0.1 s time interval:
the ICLP> Mode parameter must be set as ON-Change setting,
the tCLP> parameter must be adjusted to a wanted value (0.1 s) inside the Set \ Profi le A(or B)\
Phase overcurrent - 50/51\ I> Element \ Setpoints menu,
The threshold within CLP parameter ICLP>def must be adjusted to a wanted value inside the
Set \ Profi le A(or B)\ Phase overcurrent - 50/51\ I> Element \ Defi nite time menu.
CB position can be acquired by means one or two binary inputs; allocation of 52a and 52b functions
is available inside the Set \ Board 1(2) inputs \ Binary input IN1-1...(IN2-x) menu.
Note 1 For generator protection the CB State mode must be used
Note 2 For generator protection the MR Enable parameter must be disabled (OFF)
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