Megger torkel 820, Руководство пользователя

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T O R K E L 8 2 0 / 8 4 0 / 8 6 0
P r o g r a m m a E l e c t r i c A B
Z P - B S 0 6 E R 1 0 1
When a single
TORKEL isn’t
enough
When a single TORKEL cannot provide the current you
need, you can:
Connect one or more TXL Extra Loads to
TORKEL.
Connect two or more TORKELs in parallel.
Connect two or more TORKELs and two or
more TXL Extra Loads into a single system.
When two or more TORKELs are connected into a sin-
gle system, you will normally use the “External current
measurement” function. But in situations where it is
important for current to be regulated to the correct
value within a second or so, it is better to use two or
more TORKEL units set for internal current measure-
ment and no TXL Extra Loads since these latter must
be started manually. To obtain the total current, you
must then add the current values (amperages) shown
on all TORKEL units. The TORKEL units can be started
and stopped synchronously via the START/STOP input.
TXL Extra Loads connected
to TORKEL
TXLs are resistive loads which are unable to provide
any sort of regulation. Regulation is provided by
TORKEL which measures the total current and keeps
it constant. See the chapter headed “External cur-
rent measurement” which shows how to connect the
TXL(s) and TORKEL(s).
When TXL Extra Loads are connected to TORKEL, you
must check:
That the current flowing through the TXLs
when the test is started is not higher than
intended.
That TORKEL has enough regulation capabil-
ity a) to compensate for the drop in current
through the TXLs at the end of the test and
b) to set the current to the correct value at
the beginning of the test.
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Calculating how many
TORKELs and TXLs are
needed
1. Number of TXLs – Current flow-
ing through TXL(s) at beginning of
a test
At the beginning of the test, as high a percentage as
possible of the current must flow through the TXLs,
thereby providing the TORKEL(s) with as much reserve
regulation capability as possible. However, the current
through the TXLs must not, of course, exceed, the
desired current value (A).
Note
Remember that the internal resistances of
the TXLs can be set manually. For accurate
calculation, add the cable resistance to
the internal resistance.
A. The current in an individual TXL can be obtained by
dividing the voltage at the beginning of the test by
the internal resistance of the TXL in question (see
tables below).
B. Calculate the number of TXLs that you can connect
without exceeding the desired total current.
2. Current flowing through TXL(s)
at final voltage
A. Multiply the total current through the TXL(s) which
you obtained in step 1 above by the final voltage,
and then divide by the voltage at the beginning of
the test.
3. Number of TORKELs – for the
current regulation
The TORKEL or TORKELs in the system must regulate
the current to the desired value and compensate for
the drop in current through the TXL(s) that occurs at
the final voltage.
A. The amount of regulation needed can be obtained
by subtracting the current value (A) obtained in step
2 above from the desired current.
B. Calculate the number of TORKELs required for the
current regulation.
4. Are all of the TXLs needed?
If the total load-providing capability of the TORKEL(s)
exceeds the amount of regulation needed by a wide
margin (as set fort in step above), you can perhaps
conduct the test with fewer TXLs. If this margin is
wider than the current through one of the TXLs at the
final voltage, this TXL is not needed.