Chapter 4 Installing Hardware and Wiring
4-63
4.8.2.2 Relay Output Circuit
Relay terminals have no polarity. They can be applied to alternating current which passes through a load, or
direct current which passes through a load. The maximum current which can passes through every relay
terminal is 2 A, and the maximum current which can passes through every common terminal is 5 A. The
lifetime of a relay terminal varies with the working voltage, the load type (the power factor cosψ, the time
constant t(L/R)), and the current passing through the terminal. The relation is shown in the life cycle curve
below.
Contact Current(A)
20
0.5
0.1
0.2
30
50
0.3 0.7
1 2
200
300
500
100
1000
2000
3000
Operation(X10 )
3
120VAC Resistive
30VDC Inductive(t=7ms)
240VAC Inductive(cos 0.4)
ψ
=
120VAC Inductive(cos =0.4)
ψ
30VDC
Inductive
(t=40ms)
Relay output circuit
Direct-current power supply
Emergency stop: An external switch is used.
③
Fuse: To protect the output circuit, a fuse having a breaking capacity in the range of 5 A to 10 A is
connected to the common terminal.
Alternating-current power supply
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