MN715P
Receiving and Installation
3-4
AC Line Connections
A power disconnect should be installed between the input power service and
the control for a fail-safe method to disconnect power. The control will remain
in a powered-up condition until all input power is removed from the control and
the internal bus voltage is discharged.
Protective Devices
Recommended fuse sizes are based on the following:
115% of maximum continuous current for time delay.
150% of maximum continuous current for Fast or Very Fast action.
Note: These general size recommendations do not consider harmonic currents or
ambient temperatures greater than 40
°
C.
Be sure a suitable input power protection device is installed. Use the
recommended fuses listed in Tables 3-3 and 3-4 (Wire Size and Protection
Devices). Input and output wire size is based on the use of copper conductor
wire rated at 75
°
C. The table is specified for NEMA B motors.
Fast Action Fuses:
115/230VAC, Buss KTN
460VAC, Buss KTS
Very Fast Action
115/230VAC, Buss JJN
Fuses:
460VAC, Buss JJS
Time Delay Fuses:
115/230VAC, Buss FRN
460VAC, Buss FRS
Line Impedance
The Baldor Series 15J control requires a minimum line impedance of 1%. The
input impedance of the power lines can be determined as follows:
Measure the line to line voltage at no load and at full rated load. Use
these measured values to calculate impedance as follows:
%Impedance
+
(Volts
NoLoad
*
Volts
FullLoad
)
(Volts
NoLoad
)
100
Line Reactors
3 phase line reactors are available from Baldor. The size of the line reactor to
use is based on the maximum continuous load. If providing your own line
reactor, use the following formula to calculate the minimum inductance
required. Table 3-2 lists the input current required for this calculation. Line
reactors may be used at the control output to the motor. When used this way,
they are called Load Reactors.
L
+
(V
L
*
L
0.01)
(I
3
Ǹ
377)
Where:
L
Minimum inductance in henrys.
V
L-L
Input volts measured line to line.
0.01
Desired percentage of input impedance (1% shown).
I
Input current rating of control.
377
Constant used with 60Hz power.
Use 314 with 50Hz power.
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