Rockwell Automation DC3N DC Drive User Guide, 1/4-2HP-115/230 VAC - Manual (Page 17)

9 Installation
Observe the following guidelines when installing an isolation transformer:
· A power disconnecting device must be installed between the power line and
primary of the transformer.
· If the power disconnecting device is a circuit breaker, the circuit breaker trip
rating must be coordinated with the in-rush current (10-12 times full load current)
of the transformer.
Heat sinking
The DC3N chassis drive requires an additional heat sink, Reliance Electric® part
number DC3N-HS-00, when the continuous armature current is above 5 ADC. Use
a thermally conductive heat sink compound (such as Dow Corning® 340 Heat
Sink Compound) between the drive chassis and heat sink surface for optimum heat
transfer.
Line fusing
The DC3N drive chassis requires an external fuse for protection. Use fast acting
fuses rated for 250 VAC or higher, and approximately 150% of the maximum
armature current. Fuse only the hot leg of the AC line that connects to L1 and
leave L2 unfused when the AC line voltage is 115 VAC. Fuse both L1 and L2
when the AC line voltage is 230 VAC. Fuse blocks are included on enclosed drives
only. Table 1 lists the recommended line fuse sizes.
Table 1. Recommended Line Fuse Sizes
90 VDC Motor 180 VDC Max. DC Armature AC Line Fuse
Horsepower Horsepower Current (amps) Size (amps)
1/4 1/2 2.6 5
1/3 3/4 3.5 8
1/2 1 5.0 10
3/4 1 1/2 7.6 15
1 2 10 15