Wire the 24 VAC supply power wires from the transformer to the HOT and COM terminals on the spade terminal as shown in Figure 1 . See Table 1 for more information.
Figure 1. 24 VAC Supply Power Spade Terminal Wiring
Important:
- The supply power terminal block on the VMA18 is a two-position spade lug ( Figure 1 ). Exercise caution while rewiring the power plug when replacing an existing controller. Stray wire strands may make contact and cause a short circuit across the 24 VAC power supply.
- To maintain proper phasing when replacing the existing VMA 14xx controller with the VMA18 controller, connect the power wire from 24 VAC: 1 terminal on the existing controller to the HOT power terminal on the VMA18 . Also connect the power wire from the 24 VAC: 2 terminal on the existing controller to the COM power terminal on the VMA18 controller.
The supply power wire colors may be different on transformers from other manufacturers. Refer to the transformer manufacturer’s instructions and the project installation drawings for wiring details.
Important: Connect 24
VAC supply power to the VMA
and all other network devices so that
transformer phasing is uniform across the network devices. Powering network devices
with uniform 24 VAC supply power phasing reduces noise, interference, and ground
loop problems. The VMA
does not require an earth ground connection. However,
when grounding the secondary of the 24 VAC transformer is required, only one
connection to ground should be made near the transformer.
Figure 2. Transformer Grounding
CAUTION
- Risk of Personal Injury and Property Damage
- Improper wiring of this terminal may cause a short circuit across the 24 VAC power supply on -1 models.
ATTENTION
- Risque de blessure et dégâts matériels
- Improper wiring of this terminal may cause a short circuit across the 24 VAC power supply on -1 models.
To wire the VMA 18 Series controller, complete the following steps:
- Terminate wiring per engineering drawings.
- Wire network sensors and other devices to the VMA 's SA Bus.
- Wire the N2/FC Bus in a daisy chain (see Table 1).
- Ensure that the VMA ’s device address DIP switches are set to the appropriate device address. (See Setting the device address.)
- Connect the VMA controller to 24 VAC, Class 2 power.