ATS 2140-M Series, Instruction Manual

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Zone Usage and Initial Settings/Initial Power Split:
During the ramp of the furnace to the setpoint, no
attempt is made to balance the power into zones. Equal power is applied to all zones. Due to the nature
of the furnace, and the chimney effect, the bottom zone will normally be colder than the others. Due to
the cooling effect of the top pull rod, the top zone may or may not also be colder.
After observing the temperature graphs of several tests, the situation regarding differential temperatures
may be apparent. NOTE: The relative temperatures vary as the overall temperature approaches the
setpoint. The only relevant data is the information near the setpoint.
If one zone is always significantly colder or hotter (at least 15 degrees) as the setpoint is reached, then
the initial power split may be changed to improve the balance of the zones. This will result in less time
spent in the presoak state because the computer will have fewer changes to make to get all zones within
the minor alarm limit. The test can then proceed to the programmed soak time.
NOTE: When changing this initial power split, it is important to note that if power is added to one zone, it
must be taken from another zone. The total of the three zones must still equal 300.
For example, if the bottom zone is 35 degrees low when the top zone reaches the setpoint value,
removing some of the power from the top zone and redistributing it to the bottom zone may solve the
problem. Setting the values at Top 90, Middle 100, and Bottom 110 can help. Evaluating the changes is
the only way to test its effectiveness.
If the zones are within 10-15 degrees, changing the initial split values in this section will not make
enough of a different.
Zone Power Control: This section gives the system information about furnace zone control in order to
ensure optimum temperature stability and furnace performance. The values given in the original setup
will rarely change. If a change seems necessary, contact ATS. Typical values are:
Minimum 10%
Maximum 190%
Delta 0.3°F
Interval 3.0 min
Increment 0.50%
Control Parameters: The system uses a PID algorithm to determine the power needed in each zone to
maintain the specimen temperature at a value near the specified setpoint value. Since furnaces vary
widely in size and power rating, the PID terms will probably require “tuning” in order to realize optimum
operating performance from the furnace.
The following are typical default terms that will serve as a starting point and help achieve optimal
settings:
NOTE: Unlike other setup parameters, the PID parameters may be changed while the furnace is
operating.