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264

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

, 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

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

and

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)\