Manual 26710V1
ProTechTPS Total Protection System
Woodward
47
Internal Power Supplies for Discrete Signals
Two internal 24 V power supplies are available within each ProTechTPS module
for Discrete I/O, one for driving external relay coils and one wetting voltage for
configurable inputs (when used as discrete input circuits). Each power supply
utilizes an internal circuit shutdown to protect the power supply from over-current
conditions.
One power supply channel (+24 V_P) is capable of providing 24 Vdc ±10% @
500 mA maximum output current, to power external relays. This supply is used
for relay coils driven by the Independent Trip Relay signals and Programmable
Relays. Independent Trip Relay signal connections can be made through
terminals 29 and 30 with terminal 30 as common. Coil Voltage for Programmable
Relays is on terminals 80, 81, and 82 with terminals 81 and 82 as the commons.
Refer to Figure 2-17 for wiring information.
In the Independent Trip Relay models, if total current draw through
terminals 30 and 80 exceeds 500 mA the power supply’s internal
breaker will open. Upon such a condition, all load must be removed
from the specified terminals to allow this breaker to reset.
In Voted Trip Relay models, if the total current draw through
Terminals 80 exceeds 500 mA the power supply’s internal breaker
will open. Upon such a condition, all load must be removed from the
specified terminals to allow this breaker to reset.
If additional current capability is needed, the Voter & Programmable relay
connections points may be used as controlled switch contact connection points
with an external power supply. An external supply may be used instead of the
internal supply only for the independent trip
relays or programmable relays as
shown in figure 2-16f. The external supply should be referenced to terminal 80 or
81.
In the Independent Trip Relay models, if a customer provided
external supply is used for coil voltage, it must not be the input
power with a reference connection to the 24 V EXT supply or Discrete
Supply. Referencing input power to DISCRETE PWR or 24 V EXT
causes the internal supplies to respond more readily to transients on
the power bus.
A second power supply channel (Discrete PWR) is capable of providing 24 Vdc
±10% @ 50 mA maximum output current, to power the module’s configurable
input circuitry (configured as Discrete Inputs). Power connections can be made
through terminal 37, with terminal 38 as the common. This power supply is sized
to provide power for all ten discrete inputs. Refer to Figure 2-17 for information
on the module’s internal power supply relationship.
If total current draw through terminals 37 and 38 exceed 80 mA the
power supply’s internal breaker will open. Upon such a condition, all
load must be removed from the specified terminals to allow this
breaker to reset.
If additional current capability is needed, the DI wetting voltage may come from
an external source. If an external supply is used it must be an isolated supply.
