Lighting- control systems - Intelligent Buildings and Building Automation - page 212

Dual-technology motion detectors are used for applications such as secu-
rity systems, which employ a combination of different sensing technologies.
These dual-technology detectors benefit from each type of sensor, and false
alarms are reduced. PIR technology is often paired with another model to
maximize the accuracy and reduce energy use. PIR draws less energy than
microwave detection, and so many sensors are linked so that when the PIR
sensor is tripped, it activates a microwave sensor.

10.2.5 Analogue control and digital control

In the past, light dimmers and switches were all operated manually. A leveller
or knob was used to interrupt the supply directly or to move a sliding contact.
Analogue control and digital control are the two basic means for the remote
or automatic control of lighting systems today.
Analogue control is obviously the simplest method of remote or automatic
control of dimmers and other control actuation devices that vary the voltage
or other parameters of the power supply to lamps. There are many types
of signals used for lighting control similar to the control of other systems.
Nowadays, two standard ranges of analogue signals are usually used for
lighting-control systems: 0-10 V and 1-10 V.
The 0-10 V Analog Control Protocol is defined by the Entertainment
Services and Technology Association (ESTA) in the United States. Practically
all the entertainment dimming devices offering analogue control follow the
specifications proposed by this protocol. The protocol specifications are listed
as Table 10.1 for both controlled and controlling devices respectively.
The 1-10 V standard used for the control of ballasts for fluorescent lamps
is an extension of analogue control standard IEC 60929. It specifies the
control range of 1-10 V to ensure that electrical noise does not affect sys-
tem control performance. The standard specifies only the 'minimum level',

Table 10.1 Specifications of 0-10 V analogue control of ESTA

Controlled devices Controlling devices

Control range 0-10 V Passive control source

impedance

<10 k Ω

OFF control voltage ≤ 0 V Active control source

impedance

<10 k Ω

100% or ON control
voltage

≥ 10 V Current source capacity >2 mA

Control Linear Stability at constant

output

±20 mV

Safe acceptance range -0.5 to +15 V Diode blocking capacity ≥ 10 V

Input impedance 100 k Ω ±20%