Orion System Modular VAV/Zone Controller - Manual (Page 15)

Modular Devices Transformer Sizing
120 / 24VAC
120 / 24VAC
120 / 24VAC
120 / 24VAC
80 VA
Transformer
Minimum
See Warning
Note Below
40 VA
Transformer
Minimum
See Warning
Note Below
100 VA
Transformer
Minimum
See Warning
Note Below
75 VA
Transformer
Minimum
See Warning
Note Below
Power/Comm
Board
Power/Comm
Board
Power/Comm
Board
Power/Comm
Board
Total length of all modular cables used on each branch ( A to B) cannot exceed 240 Ft.
Total length of all modular cables used on each branch ( A to B) cannot exceed 240 Ft.
A
A
A
A
12 Devices At 6 VA = 72 VA
Use 75 VA Transformer 6 Devices At 6 VA = 36 VA
Use 40 VA Transformer
16 Devices At 6 VA = 96 VA
Use 100 VA Transformer 13 Devices At 6 VA = 78 VA
Use 80 VA Transformer
6 Devices Maximum Per Branch Circuit
6 Devices Maximum Per Branch Circuit
Figure 15: Modular VAV/Zone Controller Actuator Package Transformer Sizing For Power/Comm Boards
Modular Devices - Transformer Sizing
Modular devices include the Modular VAV/Zone Controller Actuator
Package, Modular System Manager, and MiniLink Polling Device. All
of these devices can connect to each other and a Power/Comm Board
using prefabricated modular cables. See Figure 14 for Power/Comm
Board wiring and connections. When sizing transformers for these de-
vices, it is important to design your layout so that the fewest number of
Power/Comm Boards and the least number of transformers can be used.
In order to simplify wiring design and layout with modular devices, the
following rules apply:
1. Power/Comm Board maximum transformer size = 100 VA.
This is due to the board circuitry and fusing. Each modular
device is to be calculated at 6 VA. This allows for a
maximum of 16 devices per Power/Comm board. If more
than 16 devices are required, multiple Power/Comm boards
must be used. Any Slaved Zone actuators used are
considered a modular device and must be accounted for at
6 VA. each. They also must be included in the branch
circuit maximum quantity of 6. See rule #2.
2. No more than 6 modular devices allowed per branch circuit.
(Each Power/Comm board has 4 branch circuits
available on the board).
3. The longest total run per branch circuit is 240 feet. This is
due to voltage drop on the prefabricated cable. If cable runs
longer than 240 feet are required, additional Power/Comm
board(s) can be used. Each Power/Comm Board
connected that is in series with the first Power/Comm Board
would allow for an additional 240 feet of modular cable to
be added to the total cable run length.
See Figure 15 for information and some examples of transformer sizing
and branch circuit design.
Warning: Do not ground the 24 V transformer that is to be
used with the Power/Comm boards. Grounding
of the transformer will damage the Power/Comm
board and all boards connected to it. A separate
transformer must be used for each Power/Comm
board. No exceptions. Do not connect any other
devices to the transformer for the Power/Comm
board.
15 Modular ZCAP Technical Guide
Installation & Wiring