Measurement-computing USB-ERB24 Manuel d'utilisateur télécharger pdf (Page 19)

USB-ERB24 User's Guide Functional Details

The relay contacts associated that are with each relay location are listed in . Table 3-4

Table 3-4. Relay locations and associated contacts

R35, R36, R41, R43, R45, R47, R49, R51, R87, R89, R91, R93, R96,

R98, R100, R102, R103, R105, R107, R109, R112, R114, R116, R118

Relays NO contact pull-up (to USB +5 V) /

pull-down, user installed.

R37, R40, R42,R44, R46, R48, R50, R52, R88, R90, R92, R94, R95,

R97, R99, R101, R104, R106, R108, R110, R111, R113, R115, R117

Relays NC contact pull-up (to USB +5 V) /

pull-down, user installed

Relay contact protection circuit for inductive loads

When you connect an inductive load to a relay, energy stored in the inductive load can induce a large voltage

surge when you switch the relay. This voltage can severely damage the relay contacts. To limit the voltage

surge across the inductive load in a DC circuit, install a kickback diode across the inductive load. Refer to the

contact protection circuit in F . For AC loads, install a metal oxide varistor (MOV). igure 3-7

Figure 3-7. Relay contact protection circuit

Inductive

Load

Kickback

Diode

Relay

3-5

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 25 26

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Measurement-computing USB-ERB24 Manuel d'utilisateur Page 19