Closed Loop or Open Loop
The LS-101 can be used as a closed loop dev i c e or as an open
loop dev i c e. When the LS-101 can view both daylight and light
f rom the co n t ro l led electric lights, it is working as a clo s e d
loop dev i c e. When the LS-101 can only see daylight, it is
working as an open loop dev i ce.
In both cases, having adequate separation of the ON and OFF
setpoints is important. When working in closed loop mode, it
is critical to have enough separation between the ON and OFF
settings (known as deadband) to co m p e n s a te for the re d u c t i o n
of the co n t r o l led lights. If not, when the co n t r o l l ed lights
s w i t ch OFF, the light level will fall below the ON setpoint and
the lights switch back ON.
OPERATION
The LS-101 fe a t u res adjusta b l e ON and OFF setpoints, OFF
time delay as well as seve ral fe a t u res to simplify adjust m e n t .
For basic operation, these three para m e t e rs are all that may
need to be adjuste d .
W h i le the ON and OFF setpoints are independently adjusta b l e ,
the LS-101 fe a t u r es a built-in minimum deadband. There f o re ,
these two setpoints are always auto m a t i ca l l y separa ted by at
le a s t a minimum amount of deadband.
When the sensed light level drops below the ON setpoint fo r
20 seconds, the output signal switches ON. In the LS-1 0 1 ’s
d e f ault operation, this means that the LS-101 provides 24 VDC
on the output (blue wire) when the lights should be ON.
H o weve r, it is also poss i b le to invert the output sta te. (Ple a s e
see “Invert output” for further ex p l a n a t i o n . )
A d j u s ting the ON setpoint also auto m a t i ca l l y adjusts the OFF
setpoint to maintain the pro g r ammed deadband. Once the ON
setpoint is changed, you can further adjust the OFF setpoint.
In applications where the LS-101 sees the lighting from the
co n t r o l led fix t u res, it is important to have the ON and OFF
setpoint separa t ed by a deadband of at le a st as much as the
light provided by the co n t ro l l ed fix t u re.
Test Mode
The Te st mode te m p o ra r i l y shortens all of the time delays so
that the light level switching functions can be quickly te ste d .
Te st mode is invo ked in the installation pro c e s s in two ways.
• A f ter either an ON or OFF setpoint has been changed, the
L S-101 remains in Te s t mode for one minute. The LED
blinks ON and OFF ra p i d l y to indica te Te s t mode. During
this minute, te st the LS-101 operation by either blo c k i n g
the light reaching the sensor or by shining a bright light
i n to the sensor. At the end of the minute, the normal time
delays are re i n sta te d .
• Te st mode can be activa t ed for a longer period through a
menu item on the display. From the Te s t mode menu, yo u
can turn ON Te st mode for 30 minutes. Once turned ON, it
can also be turned OFF from the Te s t mode menu.
Temporary Override
When using the display and buttons, it is poss i b l e to
te m p o ra r i l y override the output ON or OFF from the display
and onboard buttons. This fe a t u r e is useful for observing that
the co r rect lights are being co n t ro l led and all other
components in the system are functioning co r re c t l y. (Ple a s e
see the Display functions for further ex p l a n a t i o n . )
Invert output
This fe a t u r e is used to co n t r ol dev i ces that re q u i r e a +24 VDC
signal when the lights should be turned OFF and 0 VDC when
the lights should be turned ON. The normal operation of the
L S-101 provides a +24 VDC signal when the lights should be
turned ON, but using this fe a t u re, the operation can be
reve rsed from the Adjustment Menu Setup display to satisfy
the applica t i o n .
Wall switch override
The LS-101 provides a connection for an optional low vo l t a g e ,
n o r m a l l y-open, momenta r y - c o n t act wall switch override.
This switch can be used to te m p o ra r i ly turn the lights ON
when the LS-101 has switched them OFF because the light
level is above the setpoint. When the wall switch is pre s s e d ,
the lights switch ON, and automatic light level co n t rol is
te m p o ra r i l y suspended for one hour. If during this period the
wall switch is pre s sed again, the override is ca n ce l ed and the
lights are re sto r ed to automatic co n t r o l .
The wall switch re q u i res a two wire momentary switch. See
F i g u re 10 for more info r m a t i o n .
Hold ON while occupied
This is an optional fe a t u r e that prohibits high light levels fro m
turning OFF the co n t r o l led light as long as the space re m a i n s
o c cupied. This fe a t u re allows energy savings from daylighting
co n t r ol while limiting impact on occupants who might be
d i s t r a c ted or annoyed if the lights switch OFF while they are in
the space .
This fe a t u r e re q u i res that the signal wire from an occ u p a n c y
sensor be co n n e c ted to the LS-101. See Figure 9.
The LS-101 will not switch OFF while an occupancy signal (+24
VDC) is present on the white wire.
This function is enabled or disabled from the display’s
A d j u s tment Menu SETUP submenu. It allows the occ u p a n c y
signal to be co n n e c t ed to the LS-101 at installation but late r
be ignored without having to disconnect it.
INSTALLATION
The LS-101 is designed to
be mounted in either of two
ways.
For suspended ceiling tile ,
a threaded nipple with a
lock nut is attached to the
L S-101. See Figure 5.
For sheetrock or other solid
s u r f a c es, first re m o ve the thre a d e d
n i p p l e by squeezing it near the
base of the LS-101. Then use the
t wo screw holes lo ca t ed under the
cove r. Screws are not prov i d e d .
S e l ect #6 pan head screw s
a p p r o p r i a te for the mounting
s u r f a c e, typica l ly about 7/8” lo n g .
page 2
Figure 5: Ceiling tile mount
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Figure 6: Removing the nipple from
the back side of LS-101