Cooper TP Workshop Manual_Scant:Layout 1 7/8 ... - Cooper Security

95EN, 85EN, 65EN5. Voltage drop to the second device = 180mA @ 20m = 0.58 (see table).6. Voltage at second node = first device voltage - voltage drop = 12.45 -0.58 = 11.87V.Voltage Drop Example 2The second example in Figure 10 shows what happens when a third deviceis connected 20 metres from the second.The voltage at each device is as follows:1. The total current being drawn at the first device = 180mA + 180mA+180mA = 540mA.2. Voltage drop to the first device = 540mA @ 20m = 1.73V (see table).3. Voltage at first device = control unit voltage - voltage drop = 13.60 -1.73 =11.87V.4. The total current being drawn at the second device = 180mA + 180mA =360mA.5. Voltage drop to the second device = 360mA @ 20m = 1.15V (see table).6. Voltage at second device = first device voltage - voltage drop = 11.87 -1.15 = 10.77V.7. The total current being drawn at the third device = 180mA.8. Voltage drop to the third device = 180mA @ 20m = 0.58V (see table).9. Voltage at third device = second device voltage - voltage drop = 10.77 -0.58 = 10.19V.The second example shows that when the third device is added to thenetwork the current drawn at each is increased and therefore the voltagedrop is also increased. The voltage level at the third device is now below the10.5V threshold and will cause problems.21 of 72