2 Expansion Options
04.09.2016 Mk8 MM Expansion Features Installation and Set-Up Guide Page 11
Exp
Option
Default Range Description
19 5 Pump Bypass Hysteresis
The pump bypass hysteresis is set at percentage from the pump bypass
switch point set in expansion option 18, and this will below the switch point
for expansion option set to 1 (pump bypass on above switch point) and
above the switch point for expansion option set to 2 (pump bypass on
below switch point).
0 Disabled
1 – 50 1% - 50%
20 0 Burner Operation on Feedwater Control Fault
For setting 0, the burner will continue to fire if there is a feedwater fault. For
setting 1 the burner will stop firing if there is a feedwater fault. If the burner
continues to fire and the water level drops below the control point to first
low, an alarm will occur and the burner will stop firing.
0 Burner runs on feedwater control fault
1 Burner stops on feedwater control fault
21 1 Function of Test Input
The test input terminal TST can be set for checking the auxiliary alarm
outputs or shunt switch. For setting 0, hold the test input continuously to
cycle through alarm outputs every two seconds. For setting 1, hold the test
input for three seconds to trigger the shunt switch operation, and to cancel
the shunt switch operation, hold the test input for a further three seconds.
See expansion options 22 and 23 for the shunt switch timings.
0 Test input operates alarm outputs test
1 Test input operates shunt switch
22 300 Shunt Switch – Time to 1
st
Low
When the shunt switch test is activated in expansion option 21, there is time
delay for the water to reach the first low level, allowing the operator to
decrease the water level. This test checks the first low alarm while the
burner continues to operate. If water does not drop to the first low level in
this time period, then MM will revert back to normal run mode and cancel
the shunt switch test.
30 – 600 Seconds
23 300 Shunt Switch – Time to 2
nd
Low
After the shunt switch has been tested for first low, there is further time
delay for the water to reach the second low level, allowing the operator to
further decrease the water level. This test checks the second low alarm
while the burner continues to operate. If water does not drop to the second
low level in this time period, the burner will turn off.
30 – 600 Seconds
24 5 Sudden Pressure Drop Trigger Rate
If the pressure drops by this value set over 3 seconds to a pressure below
the reset offset from the required pressure setpoint set in expansion option
26, then a sudden pressure drop condition is detected and the control point
will increase by a percentage set in expansion option 25.
1 – 100 PSI or 0.1 bar or 0.01 bar for low pressure sensor (depends on load
detector set in option 1 and metric/imperial units set in parameter 40)
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