User guide

Revision 1.5 Page 11 of 19
Warning
Please Note
The specifications of the product detailed on this
Set-Up Guide may change without notice. RDM
Ltd. shall not be liable for errors or for incidental
or consequential damages, directly and indirectly,
in connection with the furnishing, performance or
misuse of this product or document.
Ensure that all power is
switched off before
installing or maintaining
this product
Mercury 2 & Intuitive Mercury Mini-Pack Installation Guide
www.resourcedm.com
Stage Inputs
Inputs 1-5 can be set up as the following:
Control - Staged Operation
Staged operation requires the output relays to be “mapped” to a particular stage. Each stage, there are 5 stages, has to have at least 1
relay assigned for the controller to operate correctly. Use P-06 to define the total number of stages required. Use parameters P-50 to P-
74 to assign relays to each stage. More than one relay can be assigned to a particular stage. Relays can be assigned to a number of
stages. As the pressure rises above the target setpoint, plus the target above value, the controller will enter Stage 1 after the stage on
delay (P-07) has expired. At this point any relay assigned in Stage 1 will come on and the stage on delay timer will be reset. If the
pressure remains above the setpoint, plus the target above value and the stage on delay has expired for a second time the controller will
enter stage 2. At this point any relay assigned in Stage 2 will come on. Note if a relay has been assigned in Stage 1 but not used in Stage
2 then it will go off at this point. The reverse occurs when the pressure falls below the setpoint plus the target below value. The controller
will step down the stages using the stage off delay (P-08) until all stages are off.
For example if set to Pack and the pack has 4 Compressors the following could be set: -
Stage1 : Rly 1 =On, Stage2: Rly 1 and Rly 2 = On, Stage3: Rly 1 ,Rly 2 and Rly 3 = On. Stage4: Rly 1, Rly 2, Rly 3 and Rly 4 = On. This
would stage relay 1 through to four on after the appropriate stage on delay if the pressure is above the target setpoint and differentials.
Note : In the above example Relay 5 would be assigned as the Alarm Relay
Please note when the Condenser type is selected only the number of condenser stages is required.
Run-Proof
This is a “global” parameter if set to on then the Status fault inputs are used to prove that compressors are running. Configure the status
inputs, using either Compressor Normally Closed or Compressor Normally Open, which correspond with each relay output. If the relay
output is energised and the run proof signal isn’t returned within the specified time period then the compressor relay will go off, the
compressor will be taken out of the control strategy until the run proof has been reset and a Compressor fault alarm will be created. Note
the compressor fault alarm can be re-aliased in the Data Manager to “Run Proof” or similar. The run-proof feature uses the status fault
delay (P-40) and all run proof signals must be returned within this delay period. Run proofs are used with compressor (Comp) stages
only.
To reset the run proof for any stage, after an inspection has been carried out, and return the compressor back into the control strategy
use the display menu item tESt. The override option is used to manually turn on the compressor output. If the proof signal is returned
within the allotted time delay the compressor is allocated back into the control strategy. If the proof isn’t returned the compressor relay will
go off and remain out of the control strategy.
Another process used to reset a run proof alarm is by changing parameter P-11 from 1 to 0 (On to Off). This clears all run proof alarms
on all compressors which are currently out of the control logic due to run proof feature. Changing P-11 from 0 back to 1 (Off to On). The
compressor(s) will then be available for selection by the control logic. If the compressor is selected by the control strategy and the run
proof signal is then not returned within the allotted time delay then it will fail and will be removed from the control logic again. Alternatively
if the controller is power cycled then it will clear out any current run proof alarms.
Floating Head Pressure
When condenser control is achieved using the “Floating Head” pressure mode the temperature to pressure parameters must be used to
profile a pressure curve from the air on temperature probe for the condenser
(P-44 to P-49). The value read from the temperature probe is added to a “Condenser Offset” (P-19) and then converted to a pressure.
This converted pressure replaces the “Target Setpoint” (P-03) as the target pressure and P-03 is only used as a default; for instance
when the probe is disconnected or develops a fault. Low and high pressure levels allow for a lower and upper limit to be set for the target
pressure range and the target pressure can never be any value out with this range. The air on temperature can be read from probe inputs
1 to 5 and is settable via parameter (P-15).
Value
Type
Description
0
Unused
Input is not used
1
Probe
Set input as a probe input. For use with Condenser Float feature or as a monitor probe with no
alarm.
2
Condenser/Compressor
Normally Open
When selected apply 0V return signal to generate Condenser/Compressor Fault.
3
Condenser/Compressor
Normally Closed
When selected remove 0V return signal to generate Condenser/Compressor Fault.
4
General Normally Open
When selected apply 0V return signal to generate General Fault.
5
General Normally Closed
When selected remove 0V return signal to generate General Fault.
6
Standby Normally Open
When selected apply 0V return signal to place controller into standby and generate Standby
alarm.
7
Standby Normally Closed
When selected remove 0V return to place controller into standby and generate Standby alarm.