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photocell reading has been stored in the Set-point Low parameter. This is the
control set-point for the regulating process which tries to maintain this
photocell reading at all times by dimming or brightening the lights.
Switching the Lighting Load:
In addition to dimming the lighting load via the 1-10V output, the load can also
be controlled by the relay according to natuiral light level.This form of control is
governed by the setting of the parameter PCELL RLY. There are three options
for this parameter:-
DISABLED: In his mode the photocell has no effect upon the operation of the
relay - it will switch only according to detected occupancy.
PASSIVE: In this mode the relay will be inhibited from closing if the area is
entered when the ambient light level is above Set-point Low. If during the
period of occupancy, the light level falls below Set-point Low, then the lights will
switch on. In this mode the lights will never switch off during a period of
occupancy - no matter how bright it becomes.
ACTIVE: This is the same as PASSIVE mode except that, additionally, the
lights will switch off if the light level exceeds Set-point High even if the area is
occupied. For the switch-off to occur, the light level must persist at this high
level for the full duration of what is called a "Passing Cloud Timer" (PCT). The
PCT is usually of the same duration as the Off-delay used by the Presence
Detection logic; however when an unusually long Off-delay is configured the
PCT is automatically capped at 20 minutes. If the light level falls below Set-
point Low during a period of occupancy, then the lights are switched on
immediately without any delay.
Active Mode
Passive Mode
Set-point High
Set-point Low
Occupancy
Area Occupied =
Programming the Set-points:
1) Simple PCELL RLY Switching Control:
i) If PCELL RLY-ACTIVE switching action is required it is important that the
lights are switched on at least 15 minutes before this procedure is undertaken
to allow the tubes to reach full output. For PCELL RLY-PASSIVE switching
action this is not necessary.
ii) Download the settings already established within the Detector for non-
Photocell related features to the HP2000. Edit the Photocell setting to ACTIVE
or PASSIVE as required. Upload the whole configuration to Detector.
iii)Wait until the appropriate time of day for, or use blinds to create, the natural
light level, as measured with a light meter, below which you would want the
lights to be on and above which you would not want the lights to be on.
iv) Start the internal self-programming operation by selecting UTILITIES/SET
LIGHT LEVEL on the HP2000 and pressing and holding the "OK" button. The
Detector takes a Photocell reading, adds a small margin and stores the
resulting value as Set-point High. It then switches off the controlled lights and
takes another Photocell reading which it stores as Set-point Low. The lights
are now switched on again, completing the acknowledgement "blink". The OK
button can now be released. Note that the difference between the two Set-
point values, the Switching Hysteresis, is equal to the contribution to total light
made by the controlled luminaires. This is the ideal amount of hysteresis to
prevent oscillation without compromising control accuracy.
Lights ON =
Lights OFF =
Natural
Light
Duration of
Level
PCT
Area Unoccupied =
2) Regulating Control overlaid by PCELL RLY Switching Control
First carry out the commissioning procedure described for Regulating Only
control (under Photocell Commissioning). When the Regulating Only
commissioning procedure has been carried out the HP2000 parameter Set-
point Low within the Detector has acquired a new, non-default value. This value
should be read in a full download from the Detector to the HP2000 and retained.
The Set-point High value should now be manually edited on the HP2000 screen
to be about 25% higher in the same units, e.g. if a download from the Detector
to the HP2000 shows that 429 has been automatically stored into the Set-point
Low parameter, then the Set-point High value should be manually edited to 535
or 536. The PCELL RLY action should be set to "ACTIVE" or "PASSIVE", as
required, and the whole configuration then uploaded to the Detector.
User Overrides
The end-user can configure a number of lighting scenes that can be recalled
using a hand-held override. With an HC5 hand-held controller lighting can be
overridden OFF or ON, or a set level can be chosen. Regulating and switched
loads can be adjusted independently through a combination of OneSwitch
Dimming and the HC5 Hand-held Controller.
Wiring Examples
MS2421A
Using OneSwitch, Switched and
Analogue Outputs
Analogue Ballast
VOLT-
(MAX 6 AMPS)
FREE
OUTPUT
LIVE
NEUTRAL
EARTH
ONESWITCH
DIMMING
Momentary
push-to-make
switch
MS2421A
Using Switched Output only
LOAD
VOLT-
(MAX 6 AMPS)
FREE
OUTPUT
LIVE
NEUTRAL
EARTH
ONESWITCH
DIMMING
Momentary
push-to-make
switch
2 x MS2421A
In Parallel, using Switched
Output only
VOLT-
VOLT-
FREE
FREE
OUTPUT
OUTPUT
LIVE IN
NEUTRAL
NEUTRAL
EARTH
ONE
NC
SWITCH
Relay outputs may be connected together in parallel to cover larger areas,
however the total load on all combined relay outputs must not exceed 6 Amps.
DO NOT CONNECT DIMMING OUTPUTS TOGETHER .
1-10V
Output
+
-
NC
Analogue output
L
Permanent
or switched
N
supply
E
Please note that the Earth terminal
has no internal connection and is
used for termination only.
1-10V
Output
+
-
NC
NC
L
Permanent
or switched
N
supply
E
Please note that the Earth terminal
has no internal connection and is
used for termination only.
Any connection not shown is NO CONNECTION
LOAD
(Max 6 Amps)
LIVE IN
EARTH
ONE
NC
SWITCH
L
Permanent
N
or switched
supply
E
W4475D
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