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Example 1: The drive is required to operate from 0 to 60 Hz in response to a 0-
5 VDC speed reference signal (rather than the “normal” 0-10 VDC). Because TB5
MAX is based on a 0-10 VDC (or 4-20 mA) signal, the drive will operate at half
of the TB5 MAX value if it is given a 5 VDC signal. Therefore, setting TB5 MAX
to 120 Hz will cause the drive to run at 60 Hz when it is given a 5 VDC speed
reference signal.
NOTE: The drive can be programmed for inverse operation so that as the speed
reference increases, the drive speed will decrease, and as the speed reference
decreases, the drive speed will increase. This is accomplished by setting TB5
MIN to the desired maximum output frequency, and TB5 MAX to the desired
minimum output frequency.
Example 2: The drive is being controlled by a pressure transducer that provides
a 4-20 mA signal proportional to duct pressure. The minimum frequency desired
is 20 Hz, and the maximum is 60 Hz. Set TB5 MIN for 60 Hz, and TB5 MAX for
20 Hz. As the duct pressure rises, the output signal from the transducer will
increase, causing the speed of the drive to decrease. This results in a decrease in
duct pressure and a decreasing transducer signal. The drive responds to the
decreasing signal by increasing speed, which again raises the duct pressure. In this
way, the average duct pressure can be maintained at a certain level. If the acceleration
and deceleration rates are set too fast however, the drive will react quickly to signal
changes which will cause the drive speed to “hunt” up and down excessively.
42 TB10A OUT (TERMINAL TB-10A OUTPUT)
The analog output signal at TB-10A is proportional to the output frequency of
the drive. This parameter selects whether that signal is 0-10 VDC or 2-10 VDC.
The 2-10 VDC signal can be converted to a 4-20 mA signal by connecting a resistor
in series with the signal such that the total load resistance is 500 Ohms. If set to
NONE, the function is disabled.
NOTE: This output cannot be used with “loop-powered” devices that derive
power from a 4-20 mA signal.
43 @ TB10A (TERMINAL TB-10A SCALING)
This parameter scales the analog output signal at TB-10A. This setting is the
output frequency that is indicated when the TB-10A output measures 10VDC.
Example: The drive is part of a control system that requires a 0-5 VDC signal
(rather than 0-10 VDC) that is proportional to 0-60 Hz output frequency. The
output signal is linear, so setting this parameter to 120 Hz would yield 10 VDC at
120 Hz, and 5 VDC at 60 Hz.
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