LEESON SCR Thyristor Motor Control - Manual (Page 19)

13 Installation SPEEDMASTER™ OPERATION MANUAL
Heat sinking
Model 174311 requires an additional heat sink when the
continuous armature current is above 5 ADC. Use Leeson part
number 174314. Use a thermally conductive heat sink
compound between the drive chassis and heat sink surface for
optimum heat transfer.
No additional heat sinking is required for Model M1740007.
Line fusing
The National Electric Code requires the installation of a circuit
breaker or fuse on the incoming AC line voltage. When the AC
line voltage is 115 VAC, fuse the hot leg of the AC line that
connects to L1 and leave L2 unfused. When the AC line voltage
is 230 VAC, fuse both L1 and L2. Use a circuit breaker or fuse
that is rated approximately 150% of the maximum motor
armature current. See Table 1 (page 14) for recommended line
fuse sizes.