Mikro NX231A User manual

8. CASE DIMENSIONS
Figure 2: Case Dimensions
96 mm
96 mm
Front
110mm
100mm
90mm
90mm
1. DESCRIPTION
NX231A Earth-fault Relay User's Guide
start/
start/
2. LIGHT INDICATORS
The indicators display the status of the system as follow:
Table 1: System Status
1 = ON 0 = OFF X= don’t care, not blinking
B = blinking DT = DATA FUNC = FUNCTION
Indicator
Aux l> l>> FUNC DT Status
0 0 0 0 0 No Auxiliary power supply.
1 0 0 X X Normal condition, no tripping.
1 1 0 X X Low-set overcurrent triggered,
time delay countdown started.
1 0 1 X X High-set overcurrent triggered,
time delay countdown started.
1 B 0 B B Low-set tripped,
DT digit shows tripped value.
1 0 B B B High-set tripped,
DT digit shows tripped value.
1 X X 1 B Programming mode.
The NX321A is a microprocessor based
numerical earth-fault relay. It uses
fundamental frequency current
measurement for excellent harmonic
current rejection. The relay provides
two-element (low-set and high-set)
earth-fault protection with definite time
characteristic. The 4-digit LED indicator
on the NX231A allows the display of
present load current; recorded fault
current for last tripping; and all setting of
the relay
Rev M0 (04/19)

Table 2: FUNCTION Codes
3. PUSH-BUTTONS OPERATION
a) Trip test
b) Trip reset
c) View setting
f) Program setting
Only function codes from 4 to 8 can be programmed.
Step 1:
Step 2:
Step 3:
Step 4:
4. OUTPUT CONTACTS
Press RESET key until the function digit
shows required function.
Press the UP and DOWN key
simultaneously to enter programming
mode. The function digit will blink to
indicate the relay is in programming
Use the UP or DOWN key to select the
desired value.
To save the selected value, press the
UP and DOWN key simultaneously again.
It will exit the programming mode with the
data digits displaying new setting.
To exit programming mode without saving the
selected setting, press the RESET key once.
Figure 1: Scroll sequence
When the relay is not under tripped condition,
pressing the “RESET” key will scroll through the
various functions.
5. SOFT SWITCHES
TheNX231A incorporates 4 soft switches for system
configuration. When the function digit shows “8”, the
relay is in soft switch setting mode.
Table 3: Soft switch setting
SW
1
3
SVL
00
01
00
01
System configuration
High-set disabled.
High-set enabled.
“ ”
switch number (SW)
switch value (SVL)
200
01
10
11
The NX231A has two sets of output contact:
(i) CONTACT R1 - linked to trip signal.
The output contact can be programmed to be either
auto reset type or manual reset type.
For auto reset type, the contact remain activated until
the fault current is removed.
For manual reset type, the contact remain activated.
(i) CONTACT R2 - linked to trip or start signal.
Contact R2 linked to trip signal auto reset type.
Contact R1 linked to trip signal auto reset type.
Contact R1 linked to trip signal manual reset type.
Contact R2 linked to trip signal manual reset type.
Contact R2 linked to start signal auto reset type.
Contact R2 linked to start signal manual reset type.
7. CONNECTION DIAGRAMS
Earth Fault Relay
Indicators
Mechanical
Outputs
Setting Ranges
Low-set setting I>.....................0.10 - 5.00 A (2%-100%)
High-set setting I>> .................0.10 - 50.0 A (2%-1000%)
High-set definite time t>>.........0.00 - 100 s
Low-set definite time t > ..........0.00 - 100 s
6. TECHNICAL DATA
Ratings
Rated current In......................5 A
Frequency ...............................50 Hz or 60 Hz
Burden ....................................< 0.3 VA at In
Auxiliary Supply
NX231A-240A.........................198 ~ 265 VAC
Supply frequency ....................50 Hz or 60 Hz
VA rating ..................................3 VA typical
NX231A-110A..........................94 ~ 127 VAC
L1
L2
L3
N
NX231A
R1 R2
Auxiliary supply .....................Green LED indicator
Pick up ..................................Red LED indicator
Trip ........................................7-segment LED and
Red LED indicators
Display blinks “T.E.S.T.”, indicators I> and I>> after
test tripped.
Press and hold the “TEST” key for 3.5 seconds to
stimulate a trip.
Indicator
FUNCTION DP DATA
0 off Earth-fault current
t blink Last trip elapsed time
0 blink Previous tripped current
4 off Low-set current setting
5 off Low-set time delay setting
6 off High-set current setting
7 off High-set time delay setting
8 off Soft switch setting
d) Last Trip Elapsed Time
The function LED shows "t." and time elapsed after
last trip in day ("d"), hour ("h") and minute ("n"). If
more than 99 days, the display shows "99d" and
"oUr"
e) Trip Current Record
By default the most recent ("1") trip current is shown.
Press "UP" or "DOWN" key to show the previous
("2") and oldest ("3") trip current.
4 50 Network frequency 50 Hz
60 Network frequency 60 Hz
Thermal withstand.....................4 x Incontinuous
Rated voltage ..........................250 VAC
Continuous carry .....................5A (cos
= 1.0)
Expected electrical life ............105operations
Expected mechanical life ........5 x106
operations
Environmental conditions
Temperature ......................... -10ºC to 55ºC
Humidity ............................... 5% to 95% non-condensing
Mounting............................... Panel mounting
Dimension (mm) ................... 96(w) x 96(h) x 110(d)
Enclosure protection............. IP54 at the panel
Approximate weight.............. 0.7 kg
Accuracy
Protection thresholds ...............± 5%
Time delay.................................± 5% with a
mimimum of 50ms
Display off Mode
To toggle display off mode, press “RESET” for 10
seconds. When display off mode enabled, the
display will switch off after 6 minutes if no key is
pressed.
Press the “RESET” key to reset the relay when
tripped
(0.00 - 1.00, step 0.01; 1.00-10.0, step 0.10; 10.0-100, step 0.5)