VAV Controller—Variable Air Volume (VAV) Controller 21
The standard VAV Controller, when powered by any typical separate
isolation transformer or step-down transformer, operates reliably in an
electrical environment defined as Location Category A by the IEEE 587
Standard, that is, when installed more than 30 feet/9 meters from
electrical distribution panels or major bus and feeder systems in industrial
plants.
IEEE 587 Location Category A power line surge/noise level is specified at
6 kV, 500A (Normal Mode Ringwave).
In addition, the VAV Controller actually exceeds this category
specification by meeting these surge levels as well:
IEEE-587 style Common Mode Pulse: 1.5 kV, 3 kA
IEEE-587 style Normal Mode Pulse: 3 kV, 3 kA
IEEE-472 style Common Mode Ringwave: 1.5 kV
IEEE-472 style Normal Mode Ringwave: 500V
You must take further precautions to prevent unwanted Binary Output
cycling or other possible controller malfunctions, such as resetting, when
the controller is installed within 30 feet/9 meters of electrical distribution
panels or major bus and feeder systems in industrial plants. This electrical
environment is defined as Location Category B by the IEEE 587 Standard.
To prevent electrical noise from adversely affecting the controller:
1. Connect an MOV (Metal Oxide Varistor) across the VAV supply
transformer primary. The MOV must be rated appropriately for the
line voltage.
2. Use the list in Table 3 to select the correct MOV sold through your
electronics parts distributor.
The VAV Controller meets the following power line surge/noise standards
when you correctly apply the MOV as described.
IEEE-577 Common Mode Pulse 1.5 kV, 3 kA
Normal Mode Pulse 6 kV, 3 kA
Normal Mode Ringwave 6 kV, 500A
IEEE-472 Common Mode Ringwave 1.5 kV
Normal Mode Ringwave 500V
27F28F29FPower Line
Wiring
Transient Noise
Precautions
Surge Levels
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