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- when the unit is off, it allows the last event recorded by the relay to be checked (when pressed for about 1 second). The function
is available for 48 hours after the relay has been switched off (absence of internal or external poser supply).
- with the unit powered by PR030/B alone and with the CB off, it allows the relay to be installed in the CB (see sect. 12.6 ).
- with the unit powered by PR030/B and the CB closed, it allows the LED test (when pressed for 3 seconds) and the trip coil
operating mechanism (when pressed for 7 seconds) to be tested, with consequent opening of the CB.
- It allows the Trip signal to be reset (when pressed for about 1 second) after a tripping event, with the unit on.
WARNING: in the case of operating temperatures between -40°C and -25°C, in versions where this is envisaged,
the information only remains stored for 24 hours.
12.3.5. Test connector
Installed at the front on the relay, the connector allows PR030/B modules to be connected for temporary power supply of the relay,
and BT030-USB, PR010/T, Ekip T&P for powering, communication and testing via a PC (or via the unit itself in the case of PR010/T).
Consult the chapters dedicated to the accessory modules for further details.
12.4. PROTECTION FUNCTIONS
Depending on the model, relay PR121/P handles up to 5 independent protection functions.
Current signalling from the current sensors is processed by the microprocessor of the relay which, depending on the protection
levels and time settings, gives alarms, accomplishes timing processes and sends commands.
All the adjustable protections process according to the true root mean square value of the current values read by means of the
current sensors.
A time indication ("alarm" led) is available on the front of the unit and activates during an alarm for each protection.
It deactivates when the alarm ceases or if the protection trips.
WARNING: when activated, the protections must guarantee the following rule:
(protection L) I
I
1
Incorrect protection settings lead to an error signal from the relay (inconsistent settings).
The unit is equipped with a "protection-backup" function. If the fi rst command transmitted to the trip coil fails to open the circuit-
breaker immediately (TC partially faulty) further commands are transmitted to the trip coil until the circuit-breaker opens.
12.4.1. Protection L
- Protection L is the only adjustable protection that cannot be disabled since it is for self-protection against overloading of the
relay itself.
- - The type of curve setting is t=k/I2 and the tripping time is calculated according to the value of If:
- - For fault currents If 12ln, the tripping time of the protection is given by the expression: t(s)=
is less than 1 second, the real tripping time is forced to 1 second (t(s)= 1s.)
- - For fault currents If > 12ln, the tripping time is always t(s)= 1s.
NOTES:
- t(s)= envisaged tripping time;
- I
= fault current; given in [In] (example: 0.7In)
f
- I
, t
= protection L parameters set by the user, given in [In] and [s]
1
1
Protection L has 3 operation conditions established by the primary current level I
0.9 xI
I
No alarm, all settings possible. No time setting in progress.
f
1
0.9 xI
< I
< (1.05...1.2)
1
f
Prealarm L signal, all settings possible. No opening time setting in progress.
xI
1
(1.05...1.2) xI
< I
Alarm L signal, no setting possible. Opening time setting in progress.
1
f
WARNING: the protection L threshold range ensures that:
- the relay does not set to the alarm status for current values of less than 1.05 xI
- the relay will set to the alarm status for current values exceeding 1.2 xI
12.4.1.1. Thermal memory L
The thermal memory function can be enabled to protect the cables. It is based on the "L" parameter defi ned as trip time of the
curve (t1) selected @1.25xI1. This function can be enabled through PR010/T, or Ekip Connect.
The trip time of the release surely is 100% of the time selected after a L time has elapsed from the last overload or last trip, or
else trip time will be reduced depending on the overload and time elapsed.
IPR121/P is equipped with two instruments to make up this thermal memory. The fi rst one is only effective when the release is
powered (it also records overloads that have not lasted long enough to trip the release); the second operates even when the release
is not powered, reducing any trip times when it closes again straight after and is enabled as soon as the circuit-breaker is tripped.
The PR121/P release determines which one to use according to the situation.
12.4.2. Protection S
The protection, which can be disabled, can be the fi xed time (t=k) or inverse time (t=k/I
The tripping time with inverse time curve is given by the expression: t(s)=
Model
L6555
(protection S) I
(protection S) and I
2
2
(protezione I).
3
and by the setting of the protection itself I
f
1.
2
) type.
100 t
2
. If the calculated value is less than t
2
(I )
f
Apparatus
Doc. no.
1SDH000460R0002
9·t
1
. If the calculated value
2
(I /I )
f
1
;
1
Emax
:
1
, the
2
Scale
Page No
40/74
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