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Operation
■ Failure Detection Function
Conditions for SSR Failure Detection
Failure mode
Operating input (between
(See note 1.)
SSR short-circuit
OFF
SSR half-wave short-circuit OFF
SSR open-circuit
ON
SSR half-wave open-circuit ON
Note: 1. The contents of each of the above failure modes is as follows:
SSR short-circuit: SSR output circuit remains in the ON state.
SSR half-wave short-circuit: SSR output circuit remains in the ON state in one direction.
SSR open-circuit: SSR output circuit remains in the OFF state.
SSR half-wave open-circuit: SSR output circuit remains in the OFF state in one direction.
In addition to the failure modes listed above, detection of circuit disconnections for the load circuit is also possible. (As a rough guide,
circuit disconnection will be detected if the load impedance is greater than or equal to 1 M .)
2. The same power supply is used for both the detection and for the output circuit and so detection is not performed during power
interruptions.
3. If power supply (terminal 3) is in the open state, the SSR will still turn ON and OFF in the same way but the failure detection function and
alarm display will not operate properly.
Connection Diagrams (Main Circuit)
The following diagrams show the applicable load connection configurations for SSR failure detection.
Single Phase
G3PC
Note: 1. With 3-phase connection, so that the power supply voltage is applied between the G3PC's terminals 1/L1 and 3, connect the desired
phase to terminal 3.
2. Above mentioned products are 200V only. They are not suitable for three-phase 400V, but for three-phase 220V only.
Timing Chart
SSR ON normally
Main circuit power
supply (load side)
Operating input
(between terminals
A1 and A2)
Input LED
(yellow)
Load current
RDY/ALM LED
(Green:
; Red:
)
Alarm output
(between terminals
X1 and X2)
Note: After failure detection, if the detection conditions differ to the conditions given under Conditions for SSR Failure Detection, alarm output is
reset.
J-62
Solid State Relays with Failure Detection Function
terminals A1 and A2)
0.5 s max. (See note 2.)
3-phase Star
Connection
G3PC
G3PC
G3PC
SSR OFF normally
SSR short-circuit
Detection time
Red
3-phase Delta
Connection (3-phase,
2-wire Switching)
G3PC
SSR failure detection
Reset (See note.)
SSR open-circuit
G3PC
Alarm display
Alarm display (between
terminals X1 and X2)
(See note 3.)
Open collector transistor
output
3-phase V
Connection
G3PC
G3PC
Circuit disconnection detection on the load side
Reset (See note.)
Reset (See note.)
Load circuit disconnection
(See note 3.)
G3PC
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