WattMaster WM-WCC3-TGD-01B - Manual (Page 776)

VAV/Zone Controller Technical Guide
Operator Interface 8
Controller Inputs and Outputs
VAV/Zone Controller - Transformer
Sizing
When sizing transformers for these devices, it is important to design your
layout so that the fewest number of Power/Comm distribution boards
and the least number of transformers will be used.
In order to simplify wiring design and layout with VAV/Zone and Power/
Comm devices the following rules apply:
1. 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 transformer. If
more than 16 devices are required, multiple transformers must
be used. Any Slaved Zone actuators used must be accounted
for at 6 VA. each. They also must be included in the branch
circuit maximum quantity of 6. See rule #2 below.
2. No more than 6 modular devices allowed per branch circuit.
3. The longest total run is 240 Ft.
See Figure 5 for information and some examples of transformer sizing
and branch circuit design.
WARNING: Observe polarity when grounding the 24 V trans-
former that is to be used with the VAV/Zone Controller boards and
any other device/controller. A separate transformer can be used for
each controller or Power/Comm device.