4–57
Protection Parameters
Electronic Thermal Overload Relay Default Setting: 00
Settings:
00 Constant Torque (Recommended for inverter/vector duty motors)
01 Variable Torque (Recommended for fan-cooled standard motors)
The output current is derated as follows:
• I
output
(%) = [ ƒ
output
(Hz) x 1.2 %/Hz ] + 40%
Example:
If the rated motor current is 10A, and the output frequency is 25Hz,
the derating will be 70%, and the overload will be 10.5A (150%) for
one minute.
• I
output
(%) = [ (25Hz) (1.2 %/Hz) ] + 40% = 70%
• 10A x 70% = 7A
• 7A x 150% = 10.5A
02 Inactive
This parameter determines the drive’s motor overload protection characteristic.
The Variable Torque setting (01) allows less motor current at lower speeds than
does the Constant Torque setting (00).
Output (Hz)50
100%
I
40%
25
70%
Use this setting when using
the drives with motors which
are NOT designed
specifically for AC drive
outputs. Motors with shaft
mounted fans offer poor
cooling at low speeds,
therefore the output can be
derated at lower output
frequencies. This derated
current is for protecting the
motor at lower speeds.
Output (Hz)
100%
I
Use this setting when using
the drives with motors
designed specifically for AC
drive outputs and for running
at low speeds with high
currents. Motor currents will
be 100% throughout the
speed range, and can be up
to 150% for one minute.
P6.00
Chapter 4: AC Drive Parameters
DURAPULSE AC Drive User Manual
1st Ed. Rev. D 05/2013
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