Rockwell Automation 1336S_F_E_T_R Transistor and Thyristor (SCR) Service - Manual (Page 4)

4 Bulletin 1336 Service
6. Consult the mounting screw tightening sequence for your particular
module as shown in Figure 1-1. Temporarily torque the mounting
screws to 10% of the final torque number shown in Table 1-2.
7. Perform the final torquing of the screws in the rotation sequence
shown in Figure 1-1. All screws should be at the final rated torque
shown in Table 1-2.
Figure 1-1. Torque Mounting Sequence
8. After the rated torque has been applied to the heatsink mounting
screws, wait 45 minutes and then re-torque the fasteners to the final
rated torque again. The thermal grease tends to redistribute in a
process called "bleeding". This process tends to decrease the
mounting force the screws impose on the backplate as a function
of time. The correct magnitude of force needs to be re-established
after the time period has passed.
9. When the module is successfully mounted and torqued reinstall the
electrical leads and torque the gate and emitter lead connections to
the values shown in Table 1-2.
!
ATTENTION: Components may be damaged or
component life may suffer if temporary or final torqueing
is not performed to specification.
1
Two Point Mounting
2
2
Temporary
Torque Sequence
1
2
Final
Torque Sequence
1
Four Point Mounting
1 3
4 2
2
Temporary
Torque Sequence
1
4
Final
Torque Sequence
3
4 3
Six Point Mounting
4 6
3 1
5
Temporary
Torque Sequence
2 6 3 4 1
5
2
1 2
1
Final
Torque Sequence
4 3 6 2 5