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Teledyne API Model 480H O
3
Monitor User Manual
09421A DCN8343
Table 3-1. Status Output Definitions
Status Output
Normal Operating State
Sensor OK
Active – Connected to ground
Invalid Reading
Inactive - Open resistance
Check Lamp
Inactive - Open resistance
Pneumatic Flow
Inactive - Open resistance
3.4.3. HI-CURRENT RELAY OUTPUTS
Three form C relay outputs are provided on the interior I/O connectors (Figure 3-4).
The relays are labeled “Sys OK”, “Hi Alarm”, and “Hi-Hi Alarm.”
The relays are dry contact type form C (SPDT) relays with Normally Open (NO),
Normally Closed (NC), and Common (COM) contacts. The relays are capable of
switching up to 250 VAC, 5 A each. For maximum contact life, the relays should
only be used to drive resistive loads.
Important
IMPACT ON READINGS OR DATA
Contact life may be dramatically shortened if inductive
loads are driven without any provision for minimizing
high voltage “inductive kick” that can occur.
Table 3-2. Relay Functions for Single Stream Config
Relay #
Function
Normal Operating
State
Relay Coils
1
System OK
Closed
Energized
2
Hi Alarm
Open
De-energized
3
Hi-Hi Alarm
Open
De-energized
3.4.4. FAILSAFE OPERATION SIGNAL AND RELAY OUTPUTS
The digital Status outputs and Alarm relays can be configured using the Failsafe
Operation variable (VAR) found in the Display Setup>Vars menu. When the
Failsafe operation has been set to ON, the open collector transistors for the Status
Outputs; Invalid Reading, Check lamp and Pneumatic Flow will switch to ground
and become active.
Additionally, when the Failsafe is ON, the Alarm relays, HI Alarm and HI-HI
Alarm behave the same as the System OK relay. In that, the normal operating state,
the relay coils are energized and the (NO) contact closes.
