Benning IT 120 B 044102 Manual De Usuario

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Displayed results:
Z   

Loop impedance

  

Prospective short-circuit current

Lim 

Low limit of prospective short-circuit current value

Save displayed results for documentation purposes. Refer to chapter 6.1 for further information on 
setting functions and saving of measurement results (BENNING IT 120 B only).

Note:
-   Measurement of the loop impedance (Zs

rcd

) does not normally trip an RCD. However, the trip 

limit may be exceeded as a result of leakage current flowing to the PE protective conductor or
via a capacitive connection between L and PE conductors.

-   The specified accuracy of tested parameters is valid only if the mains voltage is stable during

the measurement.

Line impedance is a complex AC impedance within the current loop when a short-circuit to the 
neutral conductor occurs (conductive connection between phase conductor and neutral conductor 
in single-phase system or between two phase conductors in three-phase system). A 2.5 A test cur-
rent is used to perform line impedance measurement.
Prospective short-circuit current is calculated as follows:

L

n

PFC

R

scaling factor

U

I

-

x

=

N(L)

where

115 V

100 V 

≤ U

L-PE

 

< 160 V

230 V

160 V 

≤ U

L-PE

 

≤ 264 V

400 V

264 V 

< U

L-PE

 

≤ 440 V

Because of different definitions of the prospective short-circuit current IPSC in different countries
the user can set the scaling factor in the Setup menu (See chapter 4.4.2).  

How to perform line impedance measurement:
Step 1 

Select Zl/Ik (L-N/ L) (line impedance) with the function selector switch. The following 
menu is displayed:

Connect the test cable to the BENNING IT 110/ BENNING IT 120 B.

Step 2 

Set the following measuring parameters:

 

 

- 

 Fuse type

 

 

- 

 Fuse current rating

 

 

- 

 Fuse trip-out time