Precautions For Ac Output Modules; Over-Current Protection Coordination - Toshiba V Series User Manual

3.4 Precautions for AC Output Modules

(1) Over-Current Protection Coordination

One 2A fuse per 4 output points is mounted in the triac output module. Although,
taking account of protecting elements by the fuse blowing even in load short circuits,
when the fuse blows the semiconductors are subjected to considerable damage.
Therefore, take care in handling and wiring so that short circuits will not occur.
(2) If an inductive load is connected, transient overvoltage will be generated at the
output is changed to OFF. To prevent malfunction caused by this surge voltage, a
CR snubber circuit is installed in the AC output module. However, to prevent the
problem for other signal systems, install a surge absorption element in parallel with
the inductive load (install a surge absorption element as near as possible to the
inductive load).
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•
(3) Because the AC output module does not have a zero-cross function, the OFF → ON
occurs regardless of the load voltage phases. However, the ON → OFF change
occurs when load current is near zero. Check this point in load response.
6F8C0836
AC output module
Serge absorption element: Varistor, TNR, Transyl (for voltage clamping)
Bi-directional overvoltage absorption element with
a rated voltage of approx. 1.2 times of the max.
voltage (peak voltage)
Snubber (CR) circuit (for high-frequency attenuation)
3.4 Precautions for AC Output Modules
Surge absorption
L
element
∼
R( Ω)
DC resistance value of the load
2 2
I I
(I : peak value of load
C( µ F)=
-
10 20 current in ordinary time)
3
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