# Understanding Substitute Leakage Current functions in the 5320A and 5322A calibrators

Here is the description related to substitute leakage current taken from the operation manual. It is important that the 5320 or 5322A is set to a resistance value according to following formula:

R = Unominal / Id nominal   -  Rout

Unominal is either 230V or 115V, given by type of supplying mains. The voltage used is always the nominal value and cannot be changed to life mains voltage, or another value. It is selected automatically by the 5320A. Rout parameter can be set up in 5320A Menu from 0 to 5 kOhm.

Reason why this option is offered is that some safety testers calculate with 2kOhm as simulation of human body resistance when measuring substitute leakage current.

The 5320A only connects calculated resistance to the output terminals In substitute leakage current mode. The resistance value can be verified by any ohmmeter connected to the output terminals.

A substitute leakage current method often used in Appliance testers explores a voltage generator with safe low level output as source of test voltage instead of  power line voltage. DUT usually measures leakage current flowing to its sense terminal and recalculates measured current to power line nominal voltage. This recalculated current the DUT then displays as result of measuring.

The calibrator works as simple variable resistance, from the set up nominal leakage current and known nominal voltage in the power line network, the calibrator evaluates the appropriate resistance

R = Unominal / Id nominal   -  Rout

and connects the resistance to the output terminals. The calibrator does not measure leakage current in this mode. The value of the substitute leakage current  is defined by Unominal  the nominal power line voltage, 100 to 240 V, the nominal leakage current set through  Id nominal,  and output resistance of DUT source terminal Rout. Usually the Rout parameter is 2 kΩ which simulates resistance of the human body. the Rout parameter can be set up in Leakage current setup mode. The range of the setting is from 0 to 10 kΩ.

Resistor is connected to OUTPUT HI – LO terminals.

Note: The ROUT parameter significantly influences the accuracy of the
substitute leakage current calibration. Some Appliance testers are
designed with output resistance values different than 2 kΩ. Check
the DUT’s operation manual before performing this calibration.