Engineering Documentation

Table Of Contents
Appendix A Discontinued Products
Multi-Point Unit/Digital Point Unit (MPU/DPU)
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Digital Outputs
MPUs and DPUs shipped before March 1, 1989 contain one factory-installed snubber
on each DO point on the termination board. The snubber can be placed across the
normally open (NO) or normally closed (NC) terminals by means of a jumper. A
second MOV must be field installed when both the NO and NC terminals of a DO point
are being used.
No additional MOVs are required on DO points on MPUs or DPUs shipped after March
1, 1989.
Fig. 157: Field Installed MOVs.
Digital Output (DO) Wiring
Table MPU and DPU Wire Type Requirements provides DO wire run lengths for points
wired to equipment controllers.
UL and CSA listing requires the following:
The DO wiring shield must be installed in the cabinets for which they are supplied.
DO wiring must enter the MPUs and DPUs as shown.
Fig. 158: DO Entry Locations for MPU and DPU.