Myron L 729II - Manual (Page 26)

c. Hysteresis (Dead Band) Adjustment*
The hysteresis or dead band is approximately ±3% of the set
point at full scale as it leaves the factory. Under normal (most)
conditions it will not be necessary to adjust.
However, if you desire to make an adjustment please keep the
following in mind.
The adjustment is very simple and is based on set point location.
If the set point* is in the upper 75-100% of the scale, the
hysteresis control pot should be turned fully to the right.
If the set point is in the lower portion of the scale, i.e. 5-25% of
scale, the control pot may be turned fully to the left.
If you are operating in the center, 25-75% of scale, the control pot
may be adjusted in the center.
Or the hysteresis or dead band may be adjusted to tighten the
control of a particular process.
CAUTION: Adjusting the hysteresis too narrow may cause the
alarm to fluctuate (on-off) due to flow, chemical mixing or bubbles
causing the relay to chatter. This condition is to be avoided, it
could damage your valves, pumps, etc. and will eventually
damage the relay.
* Applies to both set points.
The following is assuming the front panel is already removed and
the set points have been set, if not see “Set Point Adjustment”.
1. Turn power ON.
2. Locate the Hysteresis Control (HYS1) located next to
the Set Point #1 (SP1) adjustment - it is a single turn
pot. See figure III.A.4.
3. Adjust as described in “Hysteresis (Dead Band)
Adjustment” or as desired.
4. Press set point test switch on the front panel to verify
Hysteresis is set as desired.
5. Repeat for SCO Module. See figure III.A.4.
6. Press set point test switch on the front panel to verify
Hysteresis is set as desired.
7. Turn power OFF.
d. Second Relay Connection
1. Place the user supplied relay interface cable and
watertight cable restraint into the enclosure’s
appropriate access hole.
2. Neatly connect wires to the relay connector as shown in
figure III.A.4.
e. Solid State Output Options
24VDC Unregulated 30mA max.
Same as 4. above, SOLID STATE OUTPUT.
1. Piezo Electric Alarm - PA (option)
Plug PA connector to CB as shown (See Figure
III.A.4).
2. Remote Alarm - RA™ (option)
Plug RA connector to CB as shown (See Figure
III.A.4).
3. Connect to your own alarm
Ensure your requirements do not exceed the 24VDC
Unregulated 30mA maximum.
Ensure the polarity is correct.
Attach your wires.
Attach harness connector to controller connector (RA)
per figure III.A.4.
If necessary, you may order connector with 8” Harness
part #RAH, from the Myron L Company.
REASSEMBLY:
1. Carefully reinstall the front panel, bottom first. Ensure no
wires have been pinched between enclosure and
front panel.
2. Reinstall the screws and tighten.
3. To operate, turn power ON.
22
Figure III.A.5
FRONT PANEL
Rear View
Primary/Main CB
Red LED
Primary/Main CB
Set Point Switch
SC/SCO
Red LED
LOW
SC/SCO
Set Point
Switch
Green LED
Figure III.A.6
HIGH
LOW SET POINT
FRONT PANEL Primary or Main CB
Alarm/control Location
SC/SCO
Location
pH
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