Testing With Increasing Fault Current - Gossen MetraWatt M 5010 Bedienungsanleitung

Measurement
Selecting the Function
— With the function switch (2), select the nominal
fault current of the fault current circuit breaker in
the system under test.
Measuring the Contact Potential
— Move the sliding switch (7) temporarily to the front
to position Y. This starts the measuring sequence.
— Read the contact potential off the digital measured
value display (24).
Note: Take into account that the contact potential
Ug may be smaller than 1V in the case of small
earth resistances such as is often the case in
practice. In this case, the LC-display (1) shows
O TAL,
Example: Nominal fault current lan = 30MA
earth resistance Re = 102
— contact potential
Up = 30mA : 102 = 0.3V
— display O - 1V
If the contact potential Ug measured with about 13 of
the nominal fault current and calculated up to nominal
fault current lan Is >50V, the lamp ,Ug" (14) lights red.
Contact potential is displayed up to 70V; with higher
values, overflow „OL. V" is displayed.
If, during the measuring sequence, the real contact
potential takes a value of Ug>50V, the instrument
turns off for safety reasons {lamp ,Ug" (14) lights red,
display „OL V"].
Limit Values for Continuously Permissible Contact
Potential
The limit for the continuously permissible contact
potential is Ug =50V with AC voltage (internationally
agreed upon). Lower values are partly specified for
Special applications; in agricultural operating facilities,
for instance Up = 25V.
Tripping Test
— Within the turn-on time of 15 s, temporarily move
the sliding switch (7) backwards to position I. A
tripping test is made.
When the fault current circuit breaker trips, the
lamp "Netz" (13) flashes red that is, the line voltage
has been disconnected. At the same time, the earth
resistance Is computed and displayed.
lf the contact potential Ug is >50V while a tripping test
is made, the instrument turns off for safety reasons
[lamp ,Ug" (14) lights red, display „OL V"].
If the fault current circuit breaker does not trip, the
lamp FEIT (15) lights red and „OL_" is displayed.
— Within the turn-on time of 15 s, again move the
Sliding switch (7) backwards to position | and keep
it at this position. The M 5010 now displays the
tripping time of the fault current circuit breaker (up
to 200ms).
When you release the sliding switch (7), the LC
display (1) will again show the earth resistance.
If the earth resistance is to be displayed without
conducting a tripping test, disconnect the tester from
the line before you move the sliding switch (7) to
position 1 for the first time after the measurement of the
contact potential.
30
H the line voltage is within the permissible range, the
lamp "Netz" (13) lights green, if you made the con-
nection with the test plug (6). When using the
measuring adapter (5), this lamp flashes green.
If the contact potential is too high, or if the fault current
circuit breaker does not trip, the system must be
checked (earth resistance too high, fault current circuit
breaker defective, and the like).
For a proper check of the fault current protecting
device on three-phase connections, the measurement
of the contact potential and the tripping test must be
made with all three outer conductors (L1, L2 and L3).
4.3.2 Testing with Increasing
Fault Current
Measuring Principle
To test the fault current protection circuitry, the M 5010
generates an increasing fault current of 0.3Xlan to
1.0Xlan in the line. The instrument stores the values
of contact potential and tripping current at the moment
of tripping and displays them.
When measuring with increasing fault current, you can
choose between the two limits for the contact potential
Ug =50V and Up = 25V.
Caution: If there is a leakage current in the system
when measuring, it is Superimposed on the
fault current generated by the tester and
affects the values measured for contact
potential and tripping current!
To assess a fault current protecting device,
DIN VDE 0100, Part 600, permits measuring
with increasing fault current and calculation
of the contact potential for nominal fault
current lan from the measured values.
The faster and easier measuring method
according to Section 4.3.1 "Testing with
nominal fault current — measured results
referred to nominal fault current" is prefer-
able for these reasons.
Measurement
Selecting the Function
— With the function switch (2), select the nominal
fault current of the fault current circuit breaker in
the system under test.
To prevent accidental turn-on of the function "Testing
with increasing fault current", the pushbutton
„Irz" (10) provided for this purpose is blocked. To
release the pushbutton, proceed as follows:
— Press the pushbutton Je." (10) and keep it
depressed.
— While keeping the pushbutton see (10)
depressed, move the sliding switch (7) temporarily
to the front to position Y.
— Release the pushbutton
symbol „lez Ug 50V" (26)
display (1).
„Ier" (10), when the
appears on the LC
The function "Testing with increasing fault current"
with Ug limit 50V is now turned on. By repeated
pressing of the pushbutton Je" (10) — approximately
for 1 s at a time - you can successively select the
following functions: