Cooper Security M2000 User's Guide download pdf (Page 21)

Engineering Manual Introduction

The voltage at each device is as follows:

1. The total current being drawn at the first device = 120mA + 120mA +120mA = 360mA.

2. Voltage drop to the first device = 360mA @ 20m = 1.15V (see table).

3. Voltage at first device = control unit voltage - voltage drop = 13.60 -1.15 = 12.45V.

4. The total current being drawn at the second device = 120mA + 120mA = 240mA.

5. Voltage drop to the second device = 240mA @ 20m = 0.79V (see table).

6. Voltage at second device = first device voltage - voltage drop = 12.45 - 0.79 = 11.66V.

7. The total current being drawn at the third device = 120mA.

8. Voltage drop to the third device = 120mA @ 20m = 0.38V (see table).

9. Voltage at third device = second device voltage - voltage drop = 11.66 - 0.38 = 11.28V.

The second example shows that when the third device is added to the network the current

drawn at each is increased and therefore the voltage drop is also increased. The voltage levels

at the second and third devices are now below the recommended 12V threshold and may cause

problems (even though the voltages are above the absolute minimum 10.5V threshold).

Control Panel

Network

Voltage at panel Voltage at Node Voltage at Node Voltage at Node

20m

12.45 V13.60 V

Example 1

Example 2

11.66 V 11.28 V

I = 360 mA I = 240 mA

I = 120 mA

A (+)

B (-)

20m 20m

Node 1

AUX

Node = 60mA

Total = 120mA

60mA taken by detectors

Node 2

AUX

Node = 60mA

Total = 120mA

60mA taken by detectors

Node 3

AUX

Node = 60mA

Total = 120mA

60mA taken by detectors

Control Panel

Network

Voltage at panel

Voltage at Node Voltage at Node

20m

12.81 V13.60 V 12.43 V

I = 240 mA I = 120 mA

A(+)

B(-)

20m

Node 1

AUX

Node = 60mA

Total = 120mA

60mA taken by detectors

Node 2

AUX

Node = 60mA

Total = 120mA

60mA taken by detectors

Figure 5) Voltage Drop Examples 1 & 2

Reducing Voltage Drop - Method 1

The simplest way to reduce voltage drop is to double up the supply connections (A & B), which

will halve the resistance on each core and therefore halve the voltage drop. When using the

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 179 180

Comments to this Manuals

No comments

Cooper Security M2000 User's Guide Page 21

Comments to this Manuals

Related products and manuals for Security access control systems Cooper Security M2000