Precision Digital Corporation PD154-6R2-1, Инструкция по эксплуатации

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PD154 & PD158 Vigilante II Annunciators Instruction Manual
11
Switching Inductive Loads
The use of snubbers to suppress electrical noise is
strongly recommended when switching inductive loads
to prevent disrupting the microprocessor’s operation.
The snubbers also prolong the life of the relay contacts.
Suppression can be obtained with resistor-capacitor
(RC) networks assembled by the user or purchased as
complete assemblies. Refer to the following circuits for
RC network assembly and installation:
RELAY 1
NC
NO
C
C
R
C
R
+
-
L
O
A
D
Figure 13. AC and DC Loads Protection
Choose R and C as follows:
R: 0.5 to 1
Ω
for each volt across the contacts
C: 0.5 to 1 µF for each amp through closed contacts
Notes:
1. Use capacitors rated for 250 VAC.
2. RC networks may affect load release time of so-
lenoid loads. Check to confirm proper operation.
3. Install the RC network at the
annunciator
's relay
screw terminals. An RC network may also be
installed across the load. Experiment for best
results.
RELAY 1
NC
NO
C
+
-
L
O
A
D
Figure 14. Low Voltage DC Loads Protection
RC Networks (Snubbers) Available
from Precision Digital
RC networks are available from Precision Digital and
should be applied to each relay contact switching an
inductive load. Part number: PDX6901 .
External Input Types
The external Silence (SIL), Acknowledge (ACK), and
Reset (RST) inputs may be contacts (i.e. pushbut-
tons, relay contacts, etc.), open collector inputs (OC),
or TTL signals. However, throughout this manual, the
term “pushbutton” is used to describe these external
inputs. Please refer to the chart below for signal logic.
External Input Type Active When
Switch/Contact Closed
Open Collector (OC) On
TTL Low
External Pushbutton Connections
The front panel pushbuttons may also be triggered
with pushbuttons, such as Precision Digital’s
PDA2360 series of Control Stations pictured in
Figure 15
, connected to the signal connector
terminals. See
Connector Labeling
on page
9
. Switch
SIL to common for the silence pushbutton, ACK to
common for the acknowledge pushbutton, and RST to
common for the reset pushbutton.
Figure 15. Remote Operation Control Stations
The following figure shows external pushbutton wiring
connections. Do not wire-short the external pushbutton
contacts to common.
INPUT CONNECTOR
SIL RST ACK COM
Push-
Buttons
Figure 16. External Pushbutton Connections
Multiple Unit First-Out Indication
Connections
Multiple PD158 and PD154 units can keep a single
first-out channel indicated for all connected units. An
unlimited number of units may be connected. It is
recommended that all units follow the same
sequence.
The following figure shows shared first-out indication
wiring connections for 3 units. Up to 200 units may be
connected for first-out indication.
UNIT 2
F I
SIL
RST
ACK
COM
FO
F I
SIL
RST
ACK
COM
FO
UNIT 1 UNIT 3
F I
SIL
RST
ACK
COM
FO
Figure 17. System with Multiple Units Share First-Out
Use a diode with a
reverse breakdown
voltage two to three
times the circuit
voltage and forward
current at least as
large as the load
current.