Relay Operation Details - Siemens SITRANS RD300 Operating Instructions Manual

SITRANS RD300

Relay Operation Details

Overview
The relay capabilities of the meter expand its usefulness beyond simple
indication to provide users with alarm and control functions. These
capabilities include front panel alarm status LEDs as well as either 2 or
4 optional internal relays and/or 4 external relays expansion module.
Typical applications include high or low temperature, level, pressure or
flow alarms, control applications such as simple on/off pump control,
pump alternation control for up to 8 pumps, and basic batch control.
There are four basic ways the relays can be used:
1. High or Low Alarms with Latching or Non-Latching Relays
2. Simple On/Off Control with 100% Adjustable Deadband
3. Sampling (Based on Time)
4. Pump Alternation Control for up to 8 Pumps
Relays Auto Initialization
When power is applied to the meter, the front panel LEDs and alarm
relays will reflect the state of the input to the meter. The following table
indicates how the alarm LEDs and relays will react on power-up based
on the set and reset points:
HI or LO
Alarm #
Alarm
1
2
3
4
Fail-Safe Operation
The following table indicates how the relays behave based on the fail-
safe selection for each relay:
Non-Alarm State
Fail-Safe
Selection
Off Open
On Closed
Note: NO = Normally Open, NC = Normally Closed. This refers to the
condition of the relay contacts when the power to the meter is off.
A5E31917845
Set
Point
HI 1000
LO 700
LO 250
HI 450
NO NC
Closed
Open
SITRANS RD300 – OPERATING INSTRUCTIONS
Reset Power-Up
Point Reading
500
900
400
200
Alarm State
NO NC
Closed Open
Open Closed
Relay &
LED
499 Off
499 On
499 Off
499 On
Power Failure
Relays go to
non-alarm state
Relays go to
alarm state
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