Ingersoll Rand System Automation Virtual Relay Automation User Manual
Ingersoll Rand
System Automation
Virtual Relay Automation
Operator’s Manual
Before installing or starting this unit for the rst
time, this manual should be studied carefully to
obtain a working knowledge of the unit and or the
duties to be performed while operating and
maintaining the unit.
RETAIN THIS MANUAL WITH UNIT. This Technical
manual contains IMPORTANT SAFETY DATA and
should be kept with the unit at all times.
More Than Air. Answers.
Online answers: http://air.ingersollrand.com
C.C.N. : 80444433
REV. : A
DATE : DECEMBER
2008
SECTION 1 TABLE OF CONTENTS
Section 1 - table of contentS .............................2
Section 2 - Virtual relay automation ............3
21. WHY “VIRTUAL RELAY?” ..................................................3
Section 3 - Virtual relay .......................................4
31. INPUT FUNCTIONS ........................................................... 4
32. LOGIC FUNCTIONS..........................................................4
33. ONDELAY TIMER ..............................................................6
34. OFFDELAY TIMER ............................................................7
35. VIRTUAL RELAY OUTPUT STATE ..................................7
Section 4 - Specialized Virtual relayS ............ 9
41. VIRTUAL RELAYS WITH MODIFIED OUTPUT
STATES ............................................................................................9
411. CYCLING TIMER VIRTUAL RELAYS ............................ 9
412. PULSE VIRTUAL RELAYS .............................................10
42. VIRTUAL RELAYS WITH FIXED INPUT
FUNCTIONS ................................................................................14
4.21. RUNNING VIRTUAL RELAY ........................................ 14
422. LOADED VIRTUAL RELAY ..........................................15
423. AVAILABLE VIRTUAL RELAY ......................................17
72. COMPRESSOR FUNCTION LIST .................................27
721. STATUS FUNCTIONS ....................................................27
73. I/O BOX FUNCTIONS .....................................................28
731. INPUT ALARM WARNING FUNCTIONS .............. 28
732. INPUT TRIP SHUTDOWN FUNCTIONS ...............29
733. INPUT SIGNAL S FUNCTIONS ...............................29
734. RELAY FUNCTIONS ......................................................30
735. STATUS FUNCTIONS ....................................................32
Section 8 - Virtual relay exampleS ................33
81. I/O BOX DRYER CONTROL ...........................................33
82. I/O BOX ISOLATION VALVE CONTROL ....................34
83. I/O BOX CONDENSATE DRAIN VALVE
CONTROL .....................................................................................35
84. I/O BOX WATER PUMP CONTROL .............................37
Refer to Section Indicated
Note
Important or Caution, Safety
Section 5 - phySical i/o and Virtual relayS 19
Section 6 - configuring Virtual relayS .......20
61. DEFINING AN INPUT FUNCTION ..............................20
62. STANDARD VIRTUAL RELAYS R01 R16 ..............20
63. CYCLING TIMER VIRTUAL RELAYS RT1, RT2,
RT3 ................................................................................................21
64. PULSE VIRTUAL RELAYS RP1, RP2, RP3, AND
RP4 ................................................................................................22
65. RUNNING VIRTUAL RELAY RF1 ..................................22
66. LOADED VIRTUAL RELAY LF1 .....................................23
67. AVAILABLE VIRTUAL RELAY AF1 ...............................23
Section 7 - function liStS ...................................25
71. X8I FUNCTION LIST ........................................................25
711. STATUS FUNCTIONS ....................................................25
712. SIGNAL FUNCTIONS ....................................................26
713. RELAY FUNCTIONS ......................................................26
2
SECTION 2 VIRTUAL RELAY AUTOMATION
Coil
Unpowered
Coil
Powered
0
1
The Ingersoll Rand Automation X8I system is equipped
with virtual relay capability to expand the control of a
compressed air system. Using virtual relay allows the X8I
system to control and monitor ancillary equipment such
as dryers, ow meters, dew point monitors, etc. When
virtual relay capability is activated all inputs and outputs
in the X8I system can be utilized in much the same way
a Programmable Logic Controller (PLC) would be used to
control a system. Each component in the X8I system has
a list of statuses and functions that can be used as input
functions to trigger the virtual relays. Virtual Relays are
logical constructs that are either true or false based on
the input functions but are not necessarily connected to a
physical relay output. Virtual relays can also be connected
to a physical output and thus allow control of equipment
in the system.
21. WHY “VIRTUAL RELAY?”
The name “Virtual Relay” was selected because a virtual
relay is patterned after an electromechanical relay
used in electrical circuits. A relay consists of two major
components: the coil, which detects whether or not there
is current owing, and the contacts, which change state
based on whether or not the coil is powered. A typical
relay would consist of an electromagnetic coil which
would pull the contacts closed when powered, and let
the contacts open when unpowered. Relay contacts
are designated by the state they are in when the coil
is unpowered, either Normally Open (NO) or Normally
Closed (NC). A single relay would usually have contacts of
each type.
FIGURE 1 TWO STATES OF A NORMALLY OPEN NO
RELAY
A relay allows control of a circuit by switching the current
owing through dierent parts of the circuit. Relays
can be placed in series or in parallel and sequenced
to provide digital logic to an electrical circuit. Before
electronic controllers were commonplace, relays were
used in order to perform control logic operations. The
resulting circuit diagrams looked like a ladder, and the
notation would come to be “ladder logic” that is now used
to program PLCs.
Virtual Relay got its name because it is a software
construct that is equivalent to an electromechanical
relay. It uses conditions called input functions and logic
functions that act in a similar away to the relay coil. Virtual
relays also use conditions known as output states that are
equivalent to the contacts in an electro-mechanical relay.
Virtual relays can be used as input functions to “power”
the coils of another virtual relay. The resulting logic
functions in much the same way a series of relays would.
3
4
SECTION 3 VIRTUAL RELAY
Input Function 1
Input Function 2
(
Optional
)
Logic Function
(F1,AND, OR ,
XOR )
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
(
Optional
)
Logic Function
(F1,AND, OR ,
XOR )
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Logic Function F 1
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Logic Function F 1
Virtual Relay
Output State
On Delay
Time
O Delay
Time
A virtual relay is a way for the user to create customized control for their air system using predened status registers in
the various X8I system components. Virtual relays should be thought of as a series of conditions that must be satised
in order to turn the output from false to true. The standard virtual relay consists of 5 conditions: Input Functions, Logic
Functions, On Delay Time, O Delay Time, and the Virtual Relay Output State. Each condition can only have two values,
it is either True (equal to 1) or False (equal to 0). The relationship of the conditions is shown below and the diagram is
read from left to right. The conditions on the very left must be True before moving onto the next condition until the
virtual relay output state is reached.
FIGURE 2 VIRTUAL RELAY WITH ALL CONDITIONS FALSE
31. INPUT FUNCTIONS
An input function is the rst condition that is evaluated in a virtual relay. The input function is entered by the user and
can be the running condition of the X8I, whether or not Table #1 is active, compressor 1’s load state, or even if the X8I
is currently running in Energy Control mode. The input function will constantly be evaluated and when a True value
is encountered the next condition of the virtual relay will be evaluated. In all diagrams below a green box denotes a
condition that is evaluated as True.
FIGURE 3 INPUT FUNCTION 1 HAS BEEN EVALUATED AS TRUE
For a complete set of input functions please see 6.0 – Function Lists
32. LOGIC FUNCTIONS
Each virtual relay can have up to two input functions assigned. Once the input functions have been dened the virtual
relay needs to decide how the relationship between the input functions will be evaluated. This next condition is
known as a Logic Function because it will perform a digital logic evaluation on the states of the input functions. The
available Logic Functions are F1, AND, OR, and XOR.
F1 – The logic function F1 is used when there is only one input function dened in the virtual relay. F1 evaluates the
state of the input function and if the input function is True then the logic function will also be evaluated as True. Please
note in the diagram below the Input Function 2 has been omitted.
FIGURE 4 LOGIC FUNCTION F1 HAS BEEN EVALUATED AS TRUE
If input function 1 is evaluated as False, logic function F1 will also be evaluated as false and no further conditions will
be checked.
FIGURE 5 LOGIC FUNCTION F1 HAS BEEN EVALUATED AS FALSE
AND – The logic function AND is used with two input functions. The AND function is evaluated as True when both
Input Function 1
Input Function 2
Logic Function A ND
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function AND
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function AND
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function AND
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function OR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function OR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function OR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function OR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
input function 1 and 2 are evaluated as True.
FIGURE 6 LOGIC FUNCTION AND HAS BEEN EVALUATED AS TRUE
Any other combination of input function states is evaluated as false and no further virtual relay conditions will be
checked.
FIGURE 7 LOGIC FUNCTION AND HAS BEEN EVALUATED AS FALSE
OR – The logic function OR is used with two input functions. The OR function will be evaluated as True when at least
one input function is True. The OR function will also be evaluated as True if both input functions are True.
FIGURE 8 LOGIC FUNCTION OR HAS BEEN EVALUATED AS TRUE
If both input functions are evaluated as false the logic function OR will also be evaluated as false.
FIGURE 9 LOGIC FUNCTION OR HAS BEEN EVALUATED AS FALSE
5
6
XOR – The logic function XOR (Exclusive OR) is used with two input functions. The XOR function will be evaluated as
Input Function 1
Input Function
2
Logic Function XOR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function XOR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function XOR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Input Function 2
Logic Function XOR
Virtual Relay
Output State
On Delay
Time
O Delay
Time
Input Function 1
Logic Function F 1
Virtual Relay
Output State
On Delay
Timer
(counting)
O Delay
Time
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Reset to
0)
O Delay
Time
True when one, and only one, input function is True.
FIGURE 10 LOGIC FUNCTION XOR HAS BEEN EVALUATED AS TRUE
If neither input function is evaluated True or both of the input functions are evaluated as True then the XOR logic
function is evaluated as False.
FIGURE 11 LOGIC FUNCTION XOR HAS BEEN EVALUATED AS FALSE
33. ONDELAY TIMER
Virtual relays also have the capability to be used as time delay relays. The same input function and logic function rules
described above apply, but a time factor can be added. In the case of an on-delay timer virtual relay the logic function
must remain True for a specied amount of time before the on-delay timer is evaluated as True. This time is congured
by the user and is based in seconds. The on-delay timer begins timing when the Logic Function is evaluated as True.
FIGURE 12 ONDELAY TIMER BEGINS TO COUNT
If at any point the logic function turns False the on-delay timer will stop timing and will reset to zero elapsed time. If
the logic function again turns True the on-delay timer will start over.
FIGURE 13 ONDELAY TIMER RESETS AS THE LOGIC FUNCTION HAS BEEN EVALUATED AS FALSE
Once the on-delay timer reaches the specied amount of time it is evaluated as True and the next condition in the
virtual relay can be evaluated.
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Done )
O Delay
Time
FIGURE 14 ONDELAY TIMER HAS ELAPSED AND BEEN EVALUATED AS TRUE
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
(Counting)
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
(Reset)
Input Function 1
Logic Function F 1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
(Done)
Please note that 0 seconds is a valid value for the on-delay timer duration. If the on-delay timer duration is set to zero
the on-delay timer will be evaluated as True as soon as the Logic Function is evaluated as True.
34. OFFDELAY TIMER
There is also an o-delay timer which works in an opposite way of the on-delay timer. The o delay timer be evaluated
as True as long as the logic function and on-delay timer are evaluated as True.
FIGURE 15 OFFDELAY TIMER HAS BEEN EVALUATED AS TRUE
Once the logic function is evaluated as False the o-delay timer will begin to count for a specied duration. After the
specied duration the o-delay timer will be evaluated as False. This time is congured by the user and is based in
seconds. While the O-Delay Timer is counting down the virtual relay output state will be maintained.
FIGURE 16 OFFDELAY TIMER BEGINS TO COUNT DOWN
If at any point the logic function and on-delay timer turn True the o-delay timer will stop timing and will reset to zero
elapsed time. If the logic function and on-delay timer again turn False the o-delay timer will start over.
FIGURE 17 OFF DELAY TIMER RESETS AS THE LOGIC FUNCTION AND
ONDELAY TIMER HAVE BEEN EVALUATED AS TRUE
Once the o-delay timer reaches the specied amount of time it is evaluated as False and the next condition in the
virtual relay can be evaluated.
The characteristics described so far are all considered part of a standard virtual relay. A standard virtual relay will be
designated as r01 through r16 on a virtual relay equipped component.
35. VIRTUAL RELAY OUTPUT STATE
The Virtual Relay Output State is the nal output of the virtual relay logic. The Virtual Relay Output State can be
operated in two dierent logic modes, Normally Open (NO) and Normally Closed (NC). These logic modes determine
how the output state will behave when all conditions in the virtual relay are evaluated as True.
7
8
When the virtual relay is set to operate in NO mode the virtual relay output state will be evaluated as False until all
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Delay
Timer
(Set to 0)
O Delay
Timer
conditions in the virtual relay are evaluated as True. Once all conditions are satised the output state will turn True.
This is the most common type of logic and is used in examples throughout the remainder of this manual.
FIGURE 18 NORMALLY OPEN VIRTUAL RELAY OUTPUT STATE EVALUATED AS TRUE
When the virtual relay is set to operate in NC mode the virtual relay output state will be evaluated as True until all
conditions in the virtual relay are evaluated as True. Once all conditions are satised the output state will turn False
and remain there until one of the conditions is evaluated as False.
FIGURE 19 NORMALLY CLOSED VIRTUAL RELAY EVALUATED AS FALSE
Changing the output state can be used to invert logic without changing any of the input functions. This allows for an
eective doubling of logic options.
SECTION 4 SPECIALIZED VIRTUAL RELAYS
Input Function 1
Input Function 2
Logic Function (F 1,
AND, OR , XOR )
Virtual Relay
Output State
On Timer
O Timer
Start State
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
O Timer
Start State
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
O Timer
Start State
In addition to the standard virtual relays the automation component may be equipped with specialized virtual relays
with unique behaviors. The specialized virtual relays can generally be divided into two groups; virtual relays with
unique behavior on the Virtual Relay Output State, and virtual relays with unique, xed, input functions.
41. VIRTUAL RELAYS WITH MODIFIED OUTPUT STATES
411. CYCLING TIMER VIRTUAL RELAYS
The cycling timer virtual relays are used to periodically cycle the Virtual Relay Output State between True and False
as long as all of its conditions are met. The conditions for the cycling timer virtual relay are: Input functions, logic
function, and the Virtual Relay Output State.
FIGURE 20 CYCLING TIMER VIRTUAL RELAY WITH ALL CONDITIONS FALSE
Input and Logic Functions
The cycling timer virtual relay input and logic functions are exactly the same as the standard virtual relay.
Virtual Relay Output State
The Virtual Relay Output State for a cycling timer virtual relay is “activated” when the logic function is evaluated as True.
Activated in this case does not necessarily mean the output state is evaluated as True as the output state has its own
internal conditions that must be evaluated: Start State, On Timer, and O Timer.
The Start State determines the initial True or False state of the Virtual Relay Output State when the logic function is
rst evaluated as True. If the Start State is set to True, when the logic function is rst evaluated as True the Virtual Relay
Output State will be evaluated as True and the On Timer will begin to count.
The on timer is a user adjustable setting that is either measured in seconds (rt1 and rt2) or hours (rt3). If the logic
function turns false before the on timer elapses the cycling timer virtual relay will return to the state shown in Figure 19.
After the on timer has elapsed the virtual relay output state will be evaluated as False even though the logic function is
still True. The o timer will now, however, begin to count.
FIGURE 21 VIRTUAL RELAY OUTPUT STATE WITH A START STATE
FIGURE 22 VIRTUAL RELAY OUTPUT STATE HAS BEEN EVALUATED
OF TRUE HAS BEEN EVALUATED FALSE
TRUE AND THE ON TIMER BEGINS COUNTING
9
10
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
O Timer
Start State
FIGURE 23 THE ON TIMER ELAPSES, THE VIRTUAL RELAY OUTPUT STATE
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
O Timer
Start State
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
O Timer
Start State
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Function
Select
HAS BEEN EVALUATED FALSE AND THE OFF TIMER BEGINS COUNTING
After the o timer has elapsed, the virtual relay output state will return to Figure 20 and this cycle will repeat until the
logic function is evaluated as False. The on timer and the o timer can never be active at the same time.
If the Start State is set to False, when the logic function is rst evaluated as True the Virtual Relay Output State will be
evaluated as False and the O Timer will begin to count.
FIGURE 24 VIRTUAL RELAY OUTPUT STATE WITH A START
STATE OF FALSE HAS BEEN EVALUATED FALSE
FIGURE 25 VIRTUAL RELAY OUTPUT STATE HAS BEEN EVALUATED
FALSE AND THE OFF TIMER BEGINS COUNTING
Once the o timer has elapsed the virtual relay output state turns True and the On timer begins counting. The cycling
timer virtual relay then continues to cycle as normal.
Cycling Timer Virtual Relays will be designated rt1, rt2, and rt3 on a virtual relay equipped component. Cycling Timer
Relays are not available on all components.
412. PULSE VIRTUAL RELAYS
The Pulse Virtual Relays are used to set the virtual relay output state to True for a xed period of time when the logic
function is rst evaluated as True. The conditions for the Pulse Virtual Relay are the Input Functions, Logic Function,
and Virtual Relay Output State.
FIGURE 26 PULSE VIRTUAL RELAY WITH ALL CONDITIONS FALSE
Input and Logic Functions
The Pulse Virtual Relay input and logic functions are exactly the same as the standard virtual relay.
Virtual Relay Output State
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Function
Select = 0
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Function
Select = 0
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Counting
Function
Select = 1
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Counting
Function
Select = 1
The virtual relay output state for a pulse relay reacts to a True logic function evaluation dependent on how the
Function Select register is set by the user. There are four possible Function Select options that all behave dierently.
Function Select 0 – When the function select register is set to 0 the virtual relay output state will always remain False
regardless of whether the logic function is evaluated as True or False.
FIGURE 27 PULSE VIRTUAL RELAY WITH FUNCTION SELECT 0 NEVER
TURNS THE OUTPUT STATE TO TRUE
Function Select 1 – When the function select register is set to 1 the virtual relay output state will be evaluated as True
when the logic function is rst evaluated as True. The on timer will begin to count. The on timer is user specied and is
measured in seconds for rP1 and in minutes for rP2.
FIGURE 28 PULSE VIRTUAL RELAY WITH FUNCTION SELECT 1
TURNS THE OUTPUT STATE TRUE
When using Function Select 1, the virtual relay output state will always remain true while the on timer is counting. If
the logic function is evaluated as false it has no eect on the output and the output remains True.
FIGURE 29 OUTPUT REMAINS TRUE WHILE THE ON TIMER IS ACTIVE
If the logic function again turns true while the virtual relay output state is still true, there is no eect, the on timer
continues counting until it has completed its full duration. After the on timer has elapsed the virtual relay output state
will turn False and remain in the False state until the logic function is evaluated as False and subsequently evaluated as
True again.
11
12
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Done
Function
Select = 1
FIGURE 30 ON TIMER ELAPSES AND THE VIRTUAL RELAY
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Counting
Function
Select = 2
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Counting
Function
Select = 2
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Reset
Function
Select = 2
OUTPUT STATE CHANGES TO FALSE
Function Select 2 – When the function select register is set to 2 the virtual relay output state will be evaluated as True
when the logic function is rst evaluated as True. The on timer will begin to count. The on timer is user specied and is
measured in seconds for rP1 and in minutes for rP2.
FIGURE 31 PULSE VIRTUAL RELAY WITH FUNCTION SELECT 2
TURNS THE OUTPUT STATE TRUE
When using Function Select 2, the virtual relay output state will always remain true while the on timer is counting. If
the logic function is evaluated as false it has no eect on the output and the output remains True.
FIGURE 32 OUTPUT REMAINS TRUE WHILE THE ON TIMER IS ACTIVE
If the logic function again turns true while the virtual relay output state is still true, the pulse will continue and the On
Timer is reset to zero and begins to count again.
FIGURE 33 LOGIC FUNCTION TRANSITIONS FROM FALSE
TO TRUE AND RESETS THE ON TIMER
After the on timer has elapsed the virtual relay output state will turn False and remain in the False state until the logic
function is evaluated as False and subsequently evaluated as True again.
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Done
Function
Select = 2
FIGURE 34 ON TIMER ELAPSES AND THE VIRTUAL RELAY
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Counting
Function
Select = 3
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Reset
Function
Select = 3
Input Function 1
Logic Function F1
Virtual Relay
Output State
On Timer
Done
Function
Select = 3
OUTPUT STATE CHANGES TO FALSE
Function Select 3 - When the function select register is set to 3 the virtual relay output state will be evaluated as True
when the logic function is rst evaluated as True.
FIGURE 35 PULSE VIRTUAL RELAY WITH FUNCTION SELECT 2
TURNS THE OUTPUT STATE TRUE
When using Function Select 3, if the logic function turns False at any time, the Virtual Relay Output State will turn False
and the on timer will be reset.
FIGURE 36 LOGIC FUNCTION EVALUATED AS FALSE CAUSES
THE VIRTUAL RELAY OUTPUT STATE TO TURN FALSE
If the logic function again turns True the on timer will begin counting from 0 and the virtual relay output state will stay
True until the on timer has elapsed.
FIGURE 37 ON TIMER ELAPSES AND THE VIRTUAL RELAY OUTPUT
STATE CHANGES TO FALSE
Pulse Virtual Relays will be designated rP1, and rP2 on a virtual relay equipped component.
Pulse Virtual Relays are not available on all components.
13
14
42. VIRTUAL RELAYS WITH FIXED INPUT FUNCTIONS
Compressor 2
Run State
Logic Function
(AND or OR)
Virtual Relay
Output State
Compressor 3
Run State
Compressor 1
Run State
Compressor X
Run State
Compressor 2
Run State
Logic Function
AND
Virtual Relay
Output State
Compressor 3
Run State
Compressor 1
Run State
Compressor X
Run State
Compressor 2
Run State
Logic Function
AND
Virtual Relay
Output State
Compressor 3
Run State
Compressor 1
Run State
Compressor X
Run State
4.21. RUNNING VIRTUAL RELAY
The Running Virtual Relay allows the user to monitor the running states of any or all compressors in the system and to
use the status as an input function. The conditions that are used for the Running Virtual Relay are the compressor run
state, the logic function, and the virtual relay output state.
FIGURE 38 RUNNING VIRTUAL RELAY WITH ALL CONDITIONS FALSE
Input Functions
For the Running Virtual Relay the input functions are predened as the running state of each compressor. The
compressor running state is considered True when the compressor’s motor is determined to be operating by the
X8I either serially or electrically. The user selects the compressors that are to be used as input functions. Any or all
compressors may be used as input functions.
Logic Functions
The Running Virtual Relay utilizes the AND and OR logic functions. These logic functions operate in exactly the same
manner as they would in a normal virtual relay. For example, the AND logic function will only be evaluated as True if all
selected compressors’ run states are evaluated as True.
FIGURE 39 ALL COMPRESSORS ARE IN A TRUE RUN STATE WHICH
CAUSES THE LOGIC FUNCTION AND OUTPUT STATE TO BE EVALUATED TRUE
Any other combination of compressor run states will cause the logic function to be evaluated as false and therefore the
virtual relay output state will be evaluated as false.
FIGURE 40 COMPRESSOR 2’S RUN STATE HAS BEEN EVALUATED AS FALSE
WHICH CAUSES THE LOGIC FUNCTION TO BE EVALUATED AS FALSE
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