User`s manual

Input and output modules Selecting I/O modules
6 – 2
Overload protective function
Fuses installed in output modules cannot be replaced. They are designed to protect external wir-
ing if the module outputs are shorted.
Therefore, output modules may not be protected from a short circuit.
If an output module becomes faulty due to any cause other than a short circuit, its fuse may not
function.
Overload and overheat protective functions for QY81P
If an overcurrent keeps flowing due to overload, heat is generated to activate the overheat pro-
tective function. This protective function is designed to protect the internal elements of the mod-
ule, not the external equipment.
The overload protective function is activated in 1 point increments in terms of 1 A to 3 A/point.
The overload protective function returns operation to normal when the load becomes a rated
load.
The overheat protective function is activated in 2 point increments (Y0/Y1, Y2/Y3, etc.) and
when overheat protection is activated, that of 2 points is activated simultaneously. By high tem-
perature of one output circuit the overload protection of other outputs may be activated.
If an output turns ON at the activation of the overheat protective function, the actual output volt-
age oscillates between 0 V and load voltage.
At the load voltage of 24 V, the average voltage during oscillation is approx. 7 V.
If the output is switched off by the overload protective function, no voltage is output.
To ensure that the output is turned OFF at the activation of the overheat protective function, use
an external load which switches OFF at 7 V or more.
The overheat protective function automatically returns operation to normal when heat reduces.