Danfoss VLT HVAC FC 100, Руководство по обслуживанию, Страница: 83 / 220

The adjustable frequency drives are designed to accept a variety of signals. First determine what
types of signals the adjustable frequency drive is receiving. There are six digital inputs (terminals
18, 19, 27, 29, 32, 33), two analog inputs (53 and 54), and the serial communication bus (68,
69). The presence of a correct reading will indicate that the desired signal has been detected by
the microprocessor of the adjustable frequency drive. See the chapter
Adjustable Frequency Drive
Inputs and Outputs
.
Using the status information displayed by the adjustable frequency drive is the best method of
locating problems of this nature. By selecting within parameter group 0-2* LCP Display, line 2 or
3 of the display can be set to indicate the signals coming in. The presence of a correct reading
indicates that the desired signal is detected by the microprocessor of the adjustable frequency
drive. This data also may be read in parameter group 16-6*.
If there is not a correct indication, the next step is to determine whether the signal is present at
the input terminals of the adjustable frequency drive. This can be performed with a voltmeter or
oscilloscope in accordance with the 6.3.16, Input Terminal Signal Test.
If the signal is present at the terminal, the control card is defective and must be replaced. If the
signal is not present, the problem is external to the adjustable frequency drive. The circuitry pro-
viding the signal along with its associated wiring must then be checked.
5.1.4 Programming Problems
Difficulty with adjustable frequency drive operation can be a result of improper programming of
the adjustable frequency drive parameters. Three areas where programming errors may affect
drive and motor operation are motor settings, references and limits, and I/O configuration. See
Drive Inputs and Outputs in Section 2.
The adjustable frequency drive must be set up correctly for the motor(s) connected to it. Param-
eters 1-20 – 1-25 must have data from the motor nameplate entered into the adjustable frequency
drive. This enables the adjustable frequency drive processor to match the adjustable frequency
drive to power characteristics of the motor. The most common result of inaccurate motor data is
the motor drawing higher than normal amounts of current to perform the task expected of it. In
such cases, setting the correct values for these parameters and performing the automatic motor
adaptation (AMA) function will usually solve the problem.
Any references or limits set incorrectly will result in less than acceptable adjustable frequency drive
performance. For instance, if maximum reference is set too low, the motor will be unable to reach
full speed. These parameters must be set according to the requirements of the particular instal-
lation. References are set in the 3-0* parameter group.
Incorrectly set I/O configuration usually results in the adjustable frequency drive not responding
to the function as commanded. It must be remembered that for every control terminal input or
output, there are corresponding parameters settings. These determine how the adjustable fre-
quency drive responds to an input signal or the type of signal present at that output. Utilizing an
I/O function must be thought of as a two step process. The desired I/O terminal must be wired
properly, and the corresponding parameter must be set accordingly. Control terminals are pro-
grammed in the 5-0* and 6-0* parameter groups.
5 Adjustable Frequency Drive and Motor Ap-
plications
High Power Service Manual for VLT
®
FC Series
Adjustable Frequency Drives
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MG.90.L1.22 - VLT ® is a registered Danfoss trademark
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