861SSRA208-DC-2 Magnecraft / Schneider Electric, 861SSRA208-DC-2 Datasheet - Page 24

• Manufacturer Part Number: 861SSRA208-DC-2
• Description: Modular Style
• Manufacturer: Magnecraft / Schneider Electric

Specifications of 861SSRA208-DC-2

• Control Voltage Range: 3 VDC to 32 VDC
• Load Voltage Rating: 24 VAC to 280 VAC
• Load Current Rating: 8 A
• Contact Form: SPST - NO
• Mounting Style: DIN Rail
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Data
24
Magnecraft
Definition
A solid state relay (SSR) can perform many tasks that an electromechanical relay
(EMR) can perform� The SSR differs in that it has no moving mechanical parts� It is
essentially an electronic device that relies on the electrical and optical properties of
semiconductors to achieve its isolation and switching function�
Principle of Operation
SSRs are similar to electromechanical relays, in that both use a control circuit and a
separate circuit for switching the load� When voltage is applied to the input of the SSR,
the relay is energized by a light emitting diode� The light from the diode is beamed
into a light sensitive semiconductor which conditions the control circuit to turn on the
output solid state switch� In the case of zero voltage crossover relays, the output solid
state switch is turned on at the zero crossing of AC voltage� Removal of the input
power disables the control circuit and the solid state switch also turns off when the
load current passes through the zero point of its cycle� Zero cross is only applied to AC
switching circuits� DC switching circuits operate at an instant on/off rate�
Advantages
When used correctly in the intended application, the SSR provides many of the
characteristics that are often difficult to find in the EMR: a high degree of reliability,
long service life, significantly reduced electromagnetic interference, fast response
and high vibration resistance are significant benefits of the SSR� The SSR has
no moving parts to wear out or arcing contacts to deteriorate, which are often the
primary cause of failure with an EMR�
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Long life (reliability) > 1E+9 operations
Zero voltage turn on, low EMI/RFI
Shock and vibration resistant
Random turn-on, proportional control
No contact bounce
EMR vs SSR Technology
EMR
SSR
LED
CURRENT
LIMITER
ARMATURE
COIL
®
PHOTODETECTOR
Solid State Relays
COUPLING
OPTICAL
MAGNETIC
COUPLING
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Arc-less switching
No acoustical noise
TTL compatible
Fast response
No moving parts
TRIGGER
MECHANICAL
CONTACTS
OUTPUT
DEVICE
(SSR)