SATEC SA300 ezPAC Operation Manual - Manual (Page 18)

Chapter 2 Device Description Device Outputs
18 SA300 Substation Automation Unit
output current. The 0-1mA and ±1mA analog outputs provide 100% overload currents
up to 2 mA and ±2mA.
Update time for analog outputs is 2-cycles (32 ms at @ 60Hz and 40 ms @ 50Hz).
Each analog output can be independently scaled to provide the desired engineering
scale and resolution (see
Programming Analog Outputs in Chapter 7).
Relay Outputs
The SA300 provides up to 32 digital outputs through four removable 8-channel relay
output modules. Each module has eight electro-mechanical relays: six 2-contact
SPST Form A and two 3-contact SPDT Form C relays.
The following table shows timing characteristics of the relays and their expected
lifetime.
Characteristic Form A Relays Form C Relays
Operate time 10 ms 15 ms
Release time 5 ms 5 ms
Bounce time 1 ms -
Mechanical endurance 10,000,000 operations 5,000,000 operations
Electrical endurance (10A/250V) 30,000 operations 100,000 operations
Each relay is independently programmable and operates in latched, unlatched, pulse
or KYZ mode.
Relay operations can be inverted so that the relay is energized in its non-active state
and de-energized when it is operated. This mode, known as “failsafe” mode, is used
for signaling purposes to send alarms when the device is not operational either due to
a fault or due to loss of power.
Latched and Unlatched Operation
Latched and unlatched mode of operation concerns local relay commands issued
from the control setpoints.
In unlatched mode, a local setpoint command sent to the relay is automatically
cleared; the relay is released when all setpoints linked to the relay return to non-
operated state.
In latched mode, the operated relay is not released automatically when the conditions
that caused the relay to operate are no longer present. To release a latched relay, an
explicit release command must be sent either from a separate setpoint, or through
communications. If the relay is locked in the operated state by a remote command,
the local release command only clears the internal latch and the relay stays in
operated state until the remote command is removed.
Pulse and KYZ Operation
Pulse mode causes a relay to produce a pulse with a predefined duration in response
to a local or remote relay command. After a pulse is expired, the command is
automatically cleared and the relay is held up in released state for at least pulse width
time before the next command is accepted.
The programmable pulse width is selected from 10 ms to 1 sec. The device scans all
relays in 1/2-cycle time intervals. This means that the actual pulse width is a multiple
of the 1/2-cycle time rounded to the nearest larger value. The programmable pulse
width does not include the relay operate and release times.
In KYZ mode, every operate command changes the present state of a relay to the
opposite state producing a transition pulse, and the relay is held up in this state for at
least pulse width time before the next command is accepted. KYZ mode is commonly
used with Form C relays to signal pulses by alternation of the two contact pairs.
Pulse and KYZ relays can be directly linked to the internal pulse sources to output
energy or time interval pulses.