12 - 13 12 - 13
12 TROUBLESHOOTING
MELSEC-ST
• Calculate the value of the resistor R as shown below.
To make the terminal-to-terminal voltage less than 11[V], the current I should be
as indicated below.
(24 - 11[V])/2.4[k
Ω
] = 5.42[mA]
Hence, select the resistor R that will give the current I higher than 5.42[mA].
• For the resistor R
5.6[k ] (Input impedance)
11[V]
11[V] / R > 5.42[mA] -
11[V] / R > 5.42 - 1.96[mA]
11[V] / 3.46[mA] / R
3.18[k ] / R
On the assumption that the resistor R of 2.7[k
Ω
] is connected, the power capacity
W of the resistor is as follows when the switch turns on.
W = (applied voltage)
2
/R
W = (28.8[V])
2
/2.7[k
Ω
] = 0.31[W]
• Since the power capacity of the resistor is determined to be 3 to 5 times larger
than the actual power consumption, select a resistor of 1 to 1.8[W].
A resistor of 2.7[k
Ω
] and 1 to 1.8[W] should therefore be connected across the
relevant terminal and COM.
Summary of Contents for MELESEC-ST
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Page 114: ...10 22 10 22 10 MOUNTING AND INSTALLATION MELSEC ST MEMO...
Page 125: ...11 11 11 11 11 EMC AND LOW VOLTAGE DIRECTIVE MELSEC ST MEMO...
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