Zapi EPS-BLI HYG - SCM Has Its Own Contactor; SCM Directly on the DC Power Rail

Page – 12/75 AFMNA0AA – EPS-BLI HYG – User Manual
4.2.2 SCM has its own contactor
Figure 4.2.2-1. SCM with its own contactor.
The best choice is to install SCM with its own contactor.
Pros:
 For turning operational, SCM does not need synchronization with another module
in the truck. SCM is immediately operative after key-on.
 An error in the TCM or PCM causes the MC to open, but SCM remains operative
during the stopping interval.
Cons:
 See 4.2.1: Bringing TCM to a safe state.
4.2.3 SCM directly on the DC Power rail
Figure 4.2.3-1. SCM directly connected to the DC power rail.
This choice is similar to the 4.2.2 case.
Pros:
 For turning operational, SCM does not need synchronization with another module
in the truck. SCM is immediately operative after key-on.
 An error in the TCM or PCM causes the MC to open, but SCM remains operative
during the stopping interval.
 Cost reduction vs. 4.2.2 (one contactor is saved).
Cons:
 Power stage of the SCM is always supplied: when connecting battery plug,
sparkles occur in the plug pins for the DC rail caps inside the SCM.
 Power stage of the SCM is always supplied: OEM (and UL) approval is required.
 See 4.2.1: Bringing TCM to a safe state.