Many Signet products offer control outputs that can be categorized into three categories: Mechanical Relay, Solid-State Relay and Open Collector. Each control output offers benefits and limitations based on the application requirements. See below for comparisons.
Open Collector
Benefits:
• Longer life than a Mechanical Relay
• No moving parts
• Can switch DC voltage only (typically < 30VDC)
• Faster ON/OFF switching capabilities than Mechanical Relays
Limitations:
• Can only be used with DC voltage
• Polarity very important when wiring
• Not recommended for use with:
• Inductive loads
• Lower voltage and current ratings than Mechanical Relays
• Typically should not use current > 25mA
Solid-State Relays
Benefits:
• Has isolated outputs (optically)
• Can switch DC voltage (typically < 40VDC)
• Can switch AC voltage (typically < 33VAC)
• Longer life than a Mechanical Relay
• No moving parts
• Faster ON/OFF switching capabilities (Equal rise/fall times)
• Typically less expensive than Mechanical Relays
Limitations:
• Not recommended for use with:
• Inductive loads (ex. Solenoid, Pumps)
• If using inductive loads, snubbers (RC Filter) can prevent IC damage
• Lower voltage and current ratings than Mechanical Relays
Mechanical Relays
Benefits:
• Can switch line voltage (typically < 120 to 240 VAC)
• Can switch DC voltage (typically < 30VDC @ 5A)
• Has a large current rating (typically 5A to 10A)
• Larger voltage and current ratings than Solid-State Relay and Open Collector Outputs
• Typically more expensive than Solid-State and Open Collector Outputs
Limitations:
• Slower ON/OFF switching capabilities than Solid-State Relay and Open Collector Outputs
• Mechanical contacts can burn/wear over time
• Snubbers (RC Filter) can prolong contact life
