Supply power terminal block - Metasys - MS-VMA1615 - MS-VMA1626 - MS-VMA 1628 - MS-VMA1630 - Field Device - VMA16 VAV Modular Assembly

VMA1615/1626/1628/1630 VAV Controllers Installation Guide

Product name
VMA16 VAV Modular Assembly
Document type
Installation Guide
Part number
Document revision
Revision date

The 24 VAC supply power terminal block is a gray, removable, 2-terminal plug that fits into a board-mounted jack on the upper left of the VMA controller.

Wire the 24 VAC supply power wires from the transformer to the HOT and COM terminals on the terminal plug as shown in the following figure. See Table 1 for more information.

Figure 1. 24 VAC supply power terminal block wiring
Important: Exercise caution while rewiring the power plug when replacing a VMA1610 or VMA1620 controller with a VMA1615 or VMA1630 controller. The supply power terminal on a new VMA is a two-position terminal block ( Figure 1 ). A VMA1610 or VMA1620 controller uses a three-position terminal block, and the center position is not used. Stray wire strands may make contact and cause a short circuit across the 24 VAC power supply.

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 controller 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 controller 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. See the following figure.
Figure 2. Transformer Grounding

  • Risk of Property Damage
  • Do not apply power to the system before checking all wiring connections. Improper wiring of this terminal may cause a short circuit across the 24 VAC power supply on VMA models. A short circuit may result in a tripped circuit breaker or blown fuse. If using a transformer with a built-in fuse, the transformer may need to be replaced.
  • Risque de dommages matériels
  • Ne mettez pas l’appareil sous tension avant d’avoir vérifié toutes les connexions du câblage. Le câblage inadéquat de cette borne peut causer un court-circuit sur l’alimentation électrique de 24 V c.a. des VMA modèles. Un court-circuit peut causer le déclenchement du disjoncteur ou le grillage d’un fusible. Si vous utilisez un transformateur avec un fusible intégré, vous pourriez devoir remplacer le transformateur.

To wire the controller, complete the following steps:

  1. Terminate wiring according the appropriate figure in Termination diagrams.
  2. Wire network sensors and other devices to the VMA 's SA Bus.
  3. Wire the FC Bus in a daisy chain.
  4. Ensure that the device address DIP switches are set to the appropriate device address (See Setting the controller number). Also, activate the EOL switch if necessary.
  5. Connect the controller to 24 VAC, Class 2 power.
Note: If you are using the VMA1615/1626/1628/1630 controller with the Wireless Field Bus System, refer to the WNC1800/ ZFR182x Pro Series Wireless Field Bus System Bulletin (LIT-12012320 ) or the ZFR Series Wireless Field Bus System Bulletin (LIT-12011336 ).