Innotech Genesis II Digital Controller (v5) Manuel d'utilisateur télécharger pdf (Page 121)

Page 121

Genesis II Installation Instructions

5-4 Cable Connection Procedures

This paragraph contains general procedures for the connection of Comms cables and checks to

ensure there are no hazardous voltages present.

The ideal situation would be that the voltages measured between the data conductors, between the

data conductors and the screen and between the data conductors, the screen and the earthed parts

of a device were 0VAC and 0VDC. In practice this will not be the case. These measurements should

be made before connecting any Comms cables to ensure that these voltages are within the specified

ratings of the RS485 ICs.

It is important to test all data conductors and the screen because only one conductor may be faulty if

the cable was damaged during installation.

The measured AC voltage is the RMS (eective) value but the ICs are subjected to the peak value of

voltages. Therefore, the AC values in the tests must be less than the DC values.

The following procedures should be performed in the order shown before application of power to the

system:

1. Ensure there are no network cables connected to any device.

2. Connect the supply conductors to all devices, ensuring that, where it is specified, the electrical

earth is connected to the device.

3. Ensure that no conductors or screens of the network cables are in contact with any device or

any metal.

4. Select the network device that is to be the earthing point for the network cables.

5. Before connecting the network cable to the selected device, check if there is a voltage dierence

between the test points on the cable and the device as shown in Figure 5-19 through to Figure

5-21, as appropriate.

6. If the voltages are less than the values shown in Figure 5-19 through to Figure 5-21, then

connect the network cable(s), including the screen to the device selected in Step 4, above.

7. For looping connections, test the two cables separately before connecting them.

8. Go to the device to be connected to the other end of the section of network cable.

9. Before connecting the network cable to this next device, check if there is a voltage dierence

between the test points on the cable and the device as shown in Figure 5-19 through to Figure

5-21, as appropriate.

10. If the voltages are less than the values shown in Figure 5-19 through to Figure 5-21, then

connect this section to the device. If the cable is looping onto the next device, test the next

section of network cable before connecting the cables.

11. A resistance check between the screen and a point connected to the electrical earth can confirm

the integrity of the screen at each stage of the connection process.

12. Continue testing and connecting one section at a time, moving away from the earthing point.

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Innotech Genesis II Digital Controller (v5) Manuel d'utilisateur Page 121