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2338_en_O
2.4.6
Relay outputs
Relay outputs can be located on either the base unit or optional I/O expansion module. Each
output channel is rated for 5 A.
Output channels are labeled as Qx where x indicates the channel. Channel numbering
starts with 0. A 1 or 2 indicates the terminals for each channel.
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Figure 2-26
Relay output connection (base unit shown)
Relay outputs are capable of switching 5 A @ 120 V AC or 5 A @ 24 V DC, regardless of the
input voltage.
Interference suppression measures on inductive loads/switching relays
Each electrical load is a mix of ohmic, capacitive, and inductive elements. Depending on the
proportion of the elements, switching these loads results in a larger or smaller load on the
switch contact.
In practice, loads are generally used with a large inductive element, such as a contactor,
solenoid valve or motor. Due to the energy stored in the coils, voltage peaks of up to a few
thousand volts may occur when the system is switched off. These high voltages cause an
arc on the controlling contact, which may destroy the contact through material vaporization
and material migration. This pulse, which is similar to a square wave pulse, emits
electromagnetic pulses over a wide frequency range (spectral elements reaching several
MHz) with a large amount of power.
To prevent such arcs from occurring, the contacts/loads must be fitted with protective
circuits. In general, the following protective circuits can be used:
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contact protective circuit
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load protective circuit
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combination of both protective circuits
Figure 2-27
Contact protective circuit (A), load protective circuit (B)
Installation and connection of Nanoline components
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