Make a motion dimmer out of your existing nondimmable fluorescent fixtures.
Method also works for incandescent lighting, including "can" lighting
Bob Bruns
Peak Demand Automation
In existing buildings it can be very hard to justify the cost of dimming. New dimmable ballasts for
fluorescent fixtures can be expensive, over $35 in most cases, and two are required per fixture.
Replacing existing fluorescent fixtures with LED fixtures may trigger expensive code upgrades to other
building features.
The Zone/Motion Relay from Peak Demand Automation is the perfect fix. It uses your existing ballasts
and adds dimming based on motion and occupancy for a fraction of the cost. The relay module is
completely compatible with all existing lighting, including incandescent lights and "can" lights.
Figure 1. shows what this looks like. The lights are automatically turned on full brightness whenever
someone enters the room. After 10 minutes without motion, half go off. Another 10 minutes without
motion and the lights go complete out, only to come back on when the space again becomes occupied.
Of course the actual times are completely adjustable and can be changed easily.
Figure 1. Dimming levels available with just two Zone/Motion Relay Modules from Peak Demand Automation
V1.0
elay Kit looks like:
Here is what the Zone/Motion Relay
Figure 2.. The contents of a Zone/Motion Relay Kit from Peak Demand Automation
The kit consists of the Zone/Motion Relay Module, which provides an adjustable timing interface
between a standard security sensor and a relay capable of switching alternating current up to 300 VAC.
The kit also includes a ceiling mount m
motion
otion detector with mounting screws, the power relay and "flag"
"
type (90°) crimp terminals so the power relay can easily fit in the ballast cavity.
A power supply to convert AC to DC is optional; converters for 120 VAC are less expensive than
converters for 277 VAC. An additional option is a flange mounting kit.
Each Zone/Motion Relay Module
odule can power up to ten motion detectors, so large rooms are not a
problem. Each Zone/Motion Relay
elay Module can drive up to 10 high current AC relays,
relays so one timer can
cover at least ten ballasts,, enough for nearly any work area.
The key to such a low cost and versatile system is the module, which is pictured in figure 3. The module
has a terminal for input power with a wide range, 12 to 60 Volts DC, so almost any power supply
suppl will
drive it. Internally
nternally it conditions output power for a motion detector to be used as an occupancy sensor:
The least expensive of which are widely available security type motion sensors. A ceiling mount sensor
is included with the kit, but these also come in corner mount room sensors. They can be mixed and
ganged as necessary, and with the output power of the module (up to 1.5 Amps) as many sensors as
required for a zone can be "or'd" (any one sensor causes the entire space to light up) together to cause
cau
the space to fully illuminate.
2
Figure 3. The Zone/Motion Relay Module has connections for all the pieces of your light dimming occupancy system.
The module has all the connections required to make a motion zone, and to set the timeout when,
without motion, the lights go out.
The input power supply is wide range. It’s designed to handle constant current LED supplies. Internally
this wide range DC supply is throttled down and regulated. Since internal regulation is linear, and most
DC power supplies are fixed wattage, an input voltage of about 15 Volts results in the maximum current
available for multiple sensors and multiple output relays.
The Sensor Power Output gives a good clean 12 Volts out. Most readily available security motion
sensors operate at 12 V nominal. With a total available current of 1.2 amps the output can power many
motion sensors.
The two sensor inputs, S+ and St connect directly to the relay output of the motion sensor. When the
sensor trips, it opens the relay and a pulse is generated internally. It is simple connection, just attach the
sensor relay to the two terminals and everything else is handled. If no sensor is attached, the motion is
disabled and the module will always be “on;” the lights will work normally. If you need a more
specialized motion sensor, such as one made by Panasonic
(https://na.industrial.panasonic.com/products/sensors/sensors-automotive-industrial-applications/pirmotion-sensor-papirs) the trigger input, St, can be used without the other sensor (S+) input being used at
all. S+ will deliver a good 12 Volt reference, but is current limited to under 60 mA. For more
information on how to use custom external sensors please contact the Peak Demand Automation
technical support team.
The Control Output is simply a switched solid state relay and provides up to one amp of current at all
times when the space is occupied, but no current after the module times out. Use with power relays
configured “Normally Open.”
The time delay sensor allows the user to select the time after occupancy is detected when the module
stays “on.” The user has the choice of 5, 10, 20, 30 and 40 minute delays. There is also a setting for
“always on” and “adj.” The Adjust (“adj”) setting times out in about two seconds and allows the installer
3
to test the system. The setting is made with a small screwdriver into a rotary switch on the outside of the
module.
The external input is primarily used for the module’s cousin, the Zone/Motion Dimmer, where it allows
an external dimming switch or daylighting module to dim the lights. Because the relay version of the
module is only capable of switching a relay, this external input is generally not used.
Figure 4 shows the schematic diagram for the dimmer with three fluorescent fixtures. The Zone/Motion
Relay has output power to drive up to 10 power relays; up to 1 amp total! The power relay included in
the kit draws just 83 mA (0.083 Amperes) from the module when energized.
4
Figure 5. shows the ballast compartment open and the relays installed inside. This installation conforms
with UL requirements and code requirements for any municipality.
Figure 5. Photo of the installation of relays into fixture with existing ballasts.
Figure 6. Close up photo of the installation of power relays.
Figure 6. shows a close-up of the two power relays installed in the fixture. In this case each power relay
powers one ballast, although a single relay could power both ballasts. The ballasts are the originals
installed with the fixture, low cost magnetic ballasts for T12 lights. Using the techniques described
herein fixtures of different styles and types can be mixed, that is fluorescent, incandescent and LED
fixtures can be zoned and the fluorescents can be of any types, T5, T8 or T12s. "Flag" type crimp
terminals (connectors) were used on the power relay terminals to keep the total height profile of the
power relays within the height of the ballast container. Those connectors are shown in the inset of Figure
6.
5
It's really easy to set up the Zone/Motion Relay. The only power connection change is to disconnect the
power line and use a relay as shown in Figure 7. Note that the relay is connected through the NO,
Normally Open, terminal. The module energizes the relay during times of occupancy. The connections
for the relay included in the kit, a Potter & Brumfeld T9AP5D52-12 are shown. Please note that the
connection blades for the control lines are narrower, at 0.187” wide than the power connections which
are 0.25” wide.
Figure 7. “Before” and “After” showing how easy it is to put a power relay in the ballast circuit.
Figure 8. A single Zone/Motion Relay can drive multiple power relays and motion sensors. Here just three are shown.
6
The Zone/Motion Relay module works with incandescent lights too:
Figure 9. Incandescent lights can be wired too, just break the power wire and route it through a power relay.
It is easy, just like fluorescent ballasts connect the power wires through a relay with the control wires
(low voltage) going to the Zone/Motion Relay Module.
Most installations will require that the power wires are contained in a grounded enclosure for safety. To
do this the relay should be in the same enclosure as the light, or enclosed in a separate junction box.
7
Figure 10. Fixtures that now dim. Note the motion detector on the ceiling.
Figure 10. shows the finished installation; all three lights in the room now dim, halfway at 10 minutes
without occupancy and full dark at 20 minutes, as illustrated in Figure 1. Of course the amount of time
that your lights will dim is completely adjustable. The motion dimmers are in the ceiling panels so that
they are always accessible without opening the other panels. Note that the only change to the room that
makes it apparent that motion relays are installed is the motion detector on the ceiling tiles.
8
Conclusion:
What you need:
•
•
•
You'll
ou'll need at one least one motion relay. Add a second motion relay for an
a intermediate light
level or a third for two.
You'll need one relay for each existing ballast or set of ballasts switched together.
together If you are
adding relays on incandescent lights, remember that wires carrying voltage over 60 Volts will
need to be in conduit.
A power supply. This will fit in the same area occupied by the ballasts. Although the output
out
rating is broad, 12 to 90 V
VDC, a 16 VDC power supply will give adequate performance.
performance
Extras:
There have been two accessories described in this article, a DC power supply and a mounting flange.
DC Power supplies:
A DC power supply is required to convert the AC power in the fixture to the DC required by the
Zone/Motion module. The module re
requires
uires a maximum of 60 VDC, and does not need to be enclosed in
a grounded enclosure. To get the lowest possible cost power supply with the highest power output we
recommend the following 15 VDC output power supplies:
•
For 120 VAC systems, Meanwell APV
APV-15-15 (16 Watt, 15 Volt)
APV-16-15
•
For 277 VAC systems, Meanwell LPF
LPF-16-15 (16 Watt, 15 Volt)
Both are UL listed and at 16 Watts output are suitable for most
installations.
Mounting Flanges:
In most cases, a module can be placed in a ceiling cavity without any mounting
hardware. In the rare case that mounting hardware is required a custom flange
can be ordered to mount the module with screws:
9
LPF-16-15