User manual

Chapter 5: Installation and Wiring
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Hardware User Manual, 4th Edition, Rev. B
Relay Outputs - Wiring Methods
Relay outputs are available for the Productivity3000. Relays are best for the following
applications:
• Loads that require higher currents than the solid-state outputs can deliver
• Cost-sensitive applications
• Some output channels need isolation from other outputs (such as when some loads require
different voltages than other loads)
Some applications in which NOT to use relays:
• Loads that require currents under 10 mA
• Loads which must be switched at high speed or heavy duty cycle
Relay outputs are available in two contact arrangements. Form
A type, or SPST (single pole, single throw) type. They are
normally open and are the simplest to use. The Form C, or
SPDT (single pole, double throw) type has a center contact
which moves and a stationary contact on either side. This
provides a normally closed contact and a normally open
contact.
The relays in some relay output modules share common
terminals, which connect to the wiper contact in each relay of
the bank. Other relay modules have relays which are completely
isolated from each other. In all cases, the module drives the
relay coil when the corresponding output point is on.
Relay with Form A contacts
Relay with Form C contacts