FC 300 Design Guide
Introduction to FC 300
The remote reference is calculated once every scan interval and initially consists of two parts:
1. X (the external reference) : A sum (see par. 3-04) of up t o four externally selected references, comprising
any combination (determined by the setting of par. 3-15, 3-16 and 3-17) of a fixed preset reference (par.
3-10), variable analog re ferences, variable digital pulse references, and various serial bus refe rence s
in whatever unit adjustable frequency drives are controlled ([Hz], [RPM], [Nm] etc.).
2. Y- (the relative reference): A sum of one fixed preset reference (par. 3-14) and
one variable analog referenc e (par. 3-18) in [%].
The two parts are combined in the following calculation: Remote reference = X + X * Y / 100%.
The catch-up / slow-down function and the freeze reference function can both be activated by digital
inputs on the adjustable frequen cy drive. They are describe d in par. group 5-1*.
The scaling of analog references is described in par. groups 6-1* and 6-2*, and the scaling
of digital pulse re ferences is describ ed in par. group 5-5*.
Reference lim it s and ranges are set in par. group 3-0*.
References and fe edb ack can be scaled in physical units (i.e. RPM, Hz, °C) or simply in % rela tin
g
to the values of par. 3-02 Minimum Refere n ce and par. 3-03 Maximum Referen ce.
In this case, all analog and pulse inputs are scaled according to the follo wing rules:
• When p a r. 3-00 Reference Range is [0] M in - Max, 0% reference equals 0 [unit], where unit
can be any unit e.g. rpm, m/s, bar etc., 100% reference equals the Max (abs (par. 3-03
Maximum Reference), abs (par. 3-02 Minimum Reference)).
• When par. 3-00 Reference Range: [1] -Max - +Max, 0% reference equals 0 [unit], -100%
reference e quals -Max Reference, 100% reference equals Max Reference.
Bus references are sc aled according to the foll owing rules:
• When par. 3-00 Reference Range is [0] Min - M ax. To obtain max resol
ution on the bus reference, the
scaling on the bus is: 0% reference equals Min Reference and 100% reference equals Max reference.
• When par. 3-00 Reference Range: [1] -Max - +Max, -100% reference equals -Max
Reference, 100% reference equals Max Reference.
Par. 3-00 Reference Range,3-02Minimum Reference and 3-03 Maximum Reference tog ethe r define the
allowed range of the sum of all r efere nc es. The sum of all references is clamped when necessary. The relation
between the resulting reference (after clampin
g) and the sum of all references is shown below.
25
MG.33.B6.22 - VLT is a registered Danfoss trademark
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