L2275
Emax UL
37/132
Doc. N°
Mod.
RH0109002
Apparatus
Scale
Page N°
13.4 Environmental characteristics
Operating temperature
-25°C ... +70°C
Storage temperature
-40°C ... +90°C
Relative Humidity
0% ... 98% with condensation
Degree of protection (with PR112 inserted in the circuit breaker)
IP 30
13.5 Inputs/outputs
13.5.1 Binary opto-insulated inputs
– K51/S or G Zin: Input SdZ S or G
13.5.2 Binary opto-insulated outputs
– K51/S or G Zout: SdZ S output or G
13.5.3
Output contacts
– K51/p1: relay output programmable by the user
– K51/µP: relay output for signalling microprocessor faulty
• Monostable contacts, only active when there is Vaux;
• Maximum changeover current: 3A – 250V AC (0.2A – 100V DC).
• Contact-contact insulation voltage: 1000V AC
– K51/Y01: relay output for signalling “release tripped”
• Bistable contact, also active in self-supply;
• Maximum changeover current: 0.5A – 125V AC (0.3A – 110V DC)
• Contact-contact insulation voltage: 750V AC
13.6 Communication bus
RS485 internal bus, 19,200 bps baud rate, ABB SACE protocol.
13.7 Protection functions
In the most complete configuration, the PR112 protection unit carries out six independent protection functions. In particular:
• Protection against overload with inverse time “L”
• Protection against short-circuit with adjustable delay “S”
• Protection against instantaneous short-circuit “I”
• Protection against earth fault with adjustable delay “G”
• Protection a fixed threshold against instantaneous short-circuit “Iinst”
• Protection against overtemperature “OT”
• “K” load control protection
Two functions (“K”) are also carried out for distinct control of loads: these are two predefined curves with threshold currents and trip times lower
than those selectable with protection “L”, which can be used for two different applications:
1. disconnection of two distinct loads;
2. connection and disconnection of a load
These protections allow single loads to be disconnected before the protection for overload “L” intervenes to definitively open the circuit-breaker.
This function is only available when there is an auxiliary power supply and when there is the external PR020/K signalling unit.
The protection allows current signal processing of the neutral pole in the following way:
1. at 50% of the phase value
2. at 100% of the phase value
The threshold values of protection functions “L”, “S”, “I” and “G” are indicated by I
1
, I
2
, I
3
and I
4
respectively, whereas the relative trip time is indicated
by t
1
, t
2
, t
3
and t
4
.
There is an indication on the display of the unit which is activated during an overload. This is disabled when the overload is finished or a protection
has tripped. Furthermore the circuit-breaker opens by means of the opening solenoid (SA), closes with the electrical protection tripped (K51/Y01)
and the corresponding yellow magnetic flag.
For the protections with fixed time with adjustable delay, the relationship implemented is the following: t = k
For the protections with inverse time, the relationship between trip time and overcurrent is given by the formula: t = k/I2
Rms and peak calculation
Protection functions “L, S and G” carry out the relative processing on the base of the true rms value of the secondary currents of the CT up to
6 In (protection G is disabled for currents higher than 4 In). For currents higher than 6 In, and for function “I”, the processing is carried out taking
into account the peak value divided by
2
, then the sinusoidal wave form is considered. This is because of incompatibility between the trip time
and the calculation time of the rms value.
13.7.1 Protection “L”
Protection “L” is the only one which cannot be disabled since it carries out self-protection against overloads of the release itself.
The trip time, inverse time, of the protection is given by the expression
where
I
f
is the fault current and
I
1
is the protection threshold.
NB: Time expressed in seconds.
for
for
(
)
I
I
t
f
75
0.
,
9
max
2
1
1
⋅
s
In
0.75
,
12
I
f
≤
In
12
I
f
>
