EWC Controls BMPlus 3000 Technical Bulletin page 9

DAMPER WIRING CONTINUED
If you need to connect numerous dampers to a single zone, or you are using dampers of unknown current draw
such as Spring Types, Isolation relays and separate power supplies may be required. Parallel as many dampers
as you want as long the total current load of the motor actuators does not exceed the VA rating of the
transformer. Other factors should also be considered, such as the full load amp rating of the isolating relay
contacts, voltage drops from long wire runs and feeder conductor sizing to junction points.
NOTE: Some older style dampers and competitor's dampers cannot be paralleled and must be isolated or wired
in tandem. Contact EWC Controls Technical Support for assistance.
Variations on this diagram and other damper solutions are available.
PC 6
PO 4
COM 1
PC 6
PO 4
COM 1
PC 6
PO 4
COM 1
PC 6
PO 4
COM 1
M
ultiple Damper Wiring on a Single Zone, using a Separate Transformer
and an Isolating Relay. Maximum of 20 Genuine ND/URDdampers per 40va transformer.
BMPlus 3000, 5000, 7000, Revision "B" Recommended Power Solutions
ND / URD's Number of Dampers Directly Connected
@ 1.5 va
per damper
3 40va
40va
40va 40va
5 40va
40va 40va
40va
7
Non-inherently current limiting transformers must have field provided over-current protection on the secondary 24 vac output. The table values
provided pertain to genuine ULTRAZONE Dampers and Competitors typical 24vac Spring loaded dampers. Included in these VA load ratings are the
correct number of thermostats, the BMPlus Zone System, and a 5% field factor. Spring loaded dampers draw higher currents & require more power.
ND / URD / SMD / BMD Dampers - Connect 24vac common to terminal 1 and 24vac hot to terminal 4. Damper should
Open. Remove 24vac hot from terminal 4 and apply to terminal 6. Damper should Close.
RDN / SMDL / BMDL Dampers - Connect 24vac common to terminal 1 and 24vac hot to terminals 2 and 4. Damper
should Open. Remove 24vac hot from terminal 4. Damper should Close.
SR / ESR / RSD Power Close / Spring Open Dampers - Connect 24vac common & hot to the two motor (M) terminals.
Damper should Close. Remove 24 vac hot. Damper should Open.
SR / ESR / RSD Power Open / Spring Close Dampers - Connect 24vac common & hot to the two motor (M) terminals.
Damper should Open. Remove 24vac hot. Damper should Close.
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX 732-446-5362
TYPICAL JUNCTION POINT
TYPICAL FEEDER CONDUCTOR
TYPICAL JUNCTION POINT
TYPICAL JUNCTION POINT
TYPICAL LOADCONDUCTORS
18 awg T-stat Wire
40va
T E S T I N G D A M P E R MOTORS
3
NO
14 - 16 awg
1
C
2
NC
R1 Isolation Relay
SPDT action with 24 vac coil
Relay is shown de-energized.
All dampers are closed.
H
C
TYPICAL FEEDER CONDUCTOR
14 - 16 awg
Separate 24vac
40va Transformer
Use Class 2
UL Listed 1585
Inherently
current limiting
transformers
only!
COIL
24 vac
One relay coil=One motor.
Don't overload your power
transformer, by connecting
too many relays.
L1
To Line Voltage
Provide over current
protection
L2
Spring Types
Number of Dampers Directly Connected
@ 6 - 10 va
per damper
50va
3 40va
60va 75va
40va
5
60va 100va
50va
7
E-Mail- info@ewccontrols.com
ZONE
MOTOR
M6
M4
M2
M1
Figure 18
75va
9