Benning IT 120 B 044102 Manual De Usuario

39

-   Loop impedance (Zs) measurement trips an RCD.

 sub-function performs measurements in supply systems equipped with an RCD. The measu-

rement current is small enough to prevent the RCD from tripping.
Modern measurement methods allow for stable and reliable results despite low measured signals.

The prospective fault current is calculated on the basis of measured resistance as follows:

P    PE

L

n

PFC

R

scaling factor

U

I

-

x

=

where

115 V

100 V 

≤ U

L-PE

 

< 160 V

230 V

160 V 

≤ U

L-PE

 

≤ 264 V

Because of different definitions of the prospective fault current I

PFC

 in different countries, the user 

can set the scaling factor in the Setup menu (see chapter 4.4.2).

How to perform the loop impedance measurement:
Step 1 

Select Zs/Ik (L-PE) (loop impedance) with the function selector switch. Use the 

/

 

keys to select the Zs

 sub-function. 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

 

 

Appendix A contains a list of different fuse types.

Follow the connection diagram shown in figure 5.29 to perform loop impedance measu-
rement. Use the Help function if necessary.

Step 4 

 Check the displayed warnings and online voltage/terminal monitor before starting the 
measurement. If OK, press the TEST key. After performing, the measurement results 
appear on the display together with the PASS/FAIL indication (if applicable).