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5.2
Information on leakage currents
5.2.1
Input configuration
Terminal module inputs occasionally receive their signal from an electronic device. Such a
device can produce leakage current when the device is in de-energized state (OFF). If this
current causes the input voltage at the terminal module to exceed 5 Volts, the circuit may not
be able to detect whether this device is switched on or off. This may lead to faulty operation.
If this occurs, a resistor must be added in parallel with the input circuit to divert a portion of
this leakage current so that the input voltage does not exceed 5 VDC. The input resistance
of the terminal module must be taken into account when selecting this resistor(2.8 kOhm for
TM15 and TM17 High Feature). The wattage of the resistor must be great enough that the
current consumption can be adapted to the output voltage of the switched-on source device.
5.2.2
Output configuration
Based on its design, the terminal module produces only 10 µA of leakage current for each
output circuit. This is well below the level that would cause an electronic device to
erroneously interpret an OFF state as an ON state. Therefore, unlike some output circuits
that can have leakage currents as great as 2 mA, the TM requires no external resistor to
divert leakage current.
TM15 / TM17 High Feature Operating Manual
Commissioning Manual, 05/2009
Application tips
5.2 Information on leakage currents
57
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