4)
Loop impedance value is displayed directly in . (>2 k
displayed if
resistance exceeds 2 k
Ω
).
High Current (20 ) measurement (0,01 resolution)
This mode measures L i v e t o E a r t h loop impedance via installation sockets o r t h e
L i v et oE a r t h or the L i v et oN e u t r a l loop impedance using the optional dual lead test
set. N o t e: This mode may cause RCDs to trip. The measurement sequence takes
5 seconds.
1 )
Turn rotary switch to ‘ 2 0 ’.
2 )
Connect
LT7
by mains cord, or using the dual test lead firmly connect
red test probe to Live and the black test probe to Neutral or to
Protective Earth (ground). Mains (line) voltage is displayed.
3 )
Test progress is indicated by a sequential display of vertical bars.
4 )
Loop impedance value is displayed directly in . N o t e : Any measurement
<0,01
Ω
will cause the display to flash, and should be investigated. (>20
displayed if resistance exceeds 20
Ω
).
High Current (PSCC) m e a s u r e m e n t
In this mode,
LT7
displays the Prospective Short Circuit Current (calculated at the
nominal supply voltage of 230V divided by loop impedance). This mode can be used
for L i v e to Earth connection via unprotected installation sockets, o r for Live to E a r t h ,
o r L i v e to Neutral connection on unprotected circuits using the optional lead set. T h i s
mode may cause RCDs to trip. The measurement sequence takes 5 seconds.
1)
Turn rotary switch to ‘PSCC’.
2)
Plug in the
LT7
, or firmly connect red test probe to Live and black
test probe to Protective Earth (ground) or to Neutral. Mains (line)
voltage is displayed.
3)
Test progress is indicated by a sequential display of vertical bars.
4)
PSCC value displayed directly in kA. (>20kA displayed if value
exceeds 19,9kA).
Earth Bond Testing
By using the earth bond test lead available as an optional extra, the
LT7
can measure the quality of Equipotential bonding within an installation.
1)
Turn rotary switch to ‘Auto’ or ‘20 ’.
2)
Firmly connect the flying lead probe to the metalwork to be tested
and plug the
LT7
into a convenient installation socket.
3)
Reading displayed will consist of socket supply (live conductor)
impedance plus the impedance of the equipotential earth bonding.
SPECIFICATION
Ranges:
20 (23Anominal)
0,01
Ω
- 19,9
Ω
±2% ±3 digits (230 V supply)
±5% ±6 digits (110 V supply)
200 /2k (15mAnominal) 1
Ω
-1,99k
Ω
±2% ±1 digit (230 V supply)
±5% ±2 digits (110 V supply)
When set to 0,1
Ω
resolution
±2% ±3 digits (230 V supply)
(±3 digits at 1
σ
typical)
PSCC (23Anominal)
0,01 - 0,99 kA
1,0 - 19,9 kA
Note: Calibration includes the test leads and plug. To maintain accuracy,
these must not be changed. See note overleaf.
Nominal System Voltage: 110 V / 230 V at 50 Hz
Voltage Accuracy:
±2% ±2 digits (when L-PE neon indicates).
Power supply:
4 x 1,5 V Alkaline cells IEC LR6 type
or
4 x 1,2 V NiCd or NiMHrechargeable cells
Auto shut off:
After 5 minutes of instrument inactivity
Battery life:
Typically 1200, one minute tests
Low Battery Indicator:
The
symbol will appear when A l k a l i n e
battery cells are almost exhausted.
Note: Battery cells should not be left in an instrument which may remain
unused for extended periods of time.
