Troubleshooting scenarios - Metasys - MS-VMA1615 - MS-VMA1626 - MS-VMA 1628 - MS-VMA1630 - Field Device - VMA16 VAV Modular Assembly

VMA1615/1626/1628/1630 VAV Controllers Installation Guide

Brand
Metasys
Product name
VMA16 VAV Modular Assembly
Document type
Installation Guide
Part number
24-10143-217
Document revision
K
Revision date
2019-10-18
Language
English

Controller is Off

Power at Primary of Transformer, 0V at Secondary or the Power at Primary Transformer, 24V at Secondary, 0V at Fuse/Breaker and Breaker/Fuse has tripped.

Possible Cause:
  1. Transformer is shorted.
  2. 24VAC powered sensor is not wired with the same polarity as the controller.
  3. SA bus device is not wired with the same polarity as the controller.

Correction:
  1. Ensure polarity of ~24 V COM / ICOM / + 15VCOM/SA BUS COM on the controller, auxiliary devices and I/O is the same.
  2. Ensure OUT1-OUT3 terminals of binary outputs are not connected to ~24 VAC COM, verify that OCOM1-OCOM3

    are not connected to ~24 VAC HOT (these terminals are internally sourced).

  3. Verify the short circuit has been resolved with an ohm-meter.
  4. Reset the breaker/fuse or replace the transformer.
    Note: When replacing the transformer, it is recommended to replace with a model that utilizes a resettable circuit braker. A circuit breaker makes solving wiring problems easier.
Verification:
  1. Disconnect the secondary of the 24 VAC transformer.
  2. Use an ohm-meter to measure between ~24 VAC HOT and COM; there should be no short circuit.
    Note: That some installations require the secondary of the Transformer to be Earth Grounded. If this is the case, verify that the Earth Ground connection is valid and not shared between multiple pieces of equipment.

Configurable output - analog mode is invalid

0–10 V output is set to 10–100%, but 0 V is at output terminals and Output is in protection mode -a state the analog portion of the configurable output goes into when it detects a wiring problem. The analog output is set to 0% regardless of the command whenever a wiring fault is detected.

Possible Cause: Power polarity mismatch between connected device and configurable output.

Correction: Ensure polarities of ~24 V COM/OCOM match and that the connected end device uses the same polarity.

Verification:
  1. Measure the output and verify that it matches the command.
  2. Disconnect the connected device and verify the commanded value is present.

Configurable output - analog mode is invalid

0–10V output has an undesirable offset of up to 1 V and Common Reference is incorrect.

Possible Cause: OCOM terminal is not connected.

Correction: Connect OCOM terminal of the configurable output to the common of the connected end device.

Verification:
  1. Measure the output and verify that it matches the command.
  2. Disconnect the connected device and verify the commanded value is present.