National Instruments CFP-RLY-421 User Manual download pdf (Page 8)

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In-Rush Current

The type of load and its in-rush current characteristics, together

with switching frequency, can cause contact welding. For loads

with in-rush current, measure the steady state current and in-rush

current to determine the proper relay. Some typical types of loads

and the in-rush current they create are summarized in the following

chart.

Status Indicators

Figure 3 shows the status indicator LEDs on the cFP-RLY-421.

Figure 3. Status Indicators

After you insert the cFP-RLY-421 into a backplane and apply

power to the network module, the green POWER indicator lights

and the cFP-RLY-421 informs the network module of its presence.

When the network module recognizes the cFP-RLY-421, it sends

initial configuration information to the cFP-RLY-421. After the

cFP-RLY-421 receives this initial information, the green READY

indicator lights and the module is in normal operating mode.

In addition to the green POWER and READY indicators, each

channel has a numbered, green output state indicator that lights

when the channel is in the ON state.

Type of Load In-Rush Current

Resistive load Steady-state current

Solenoid load 10 to 20 times the steady-state current

Motor load 5 to 10 times the steady-state current

Incandescent lamp load 10 to 15 times the steady-state current

Mercury lamp load Approximately 3 times the steady-state

current

Sodium vapor lamp load 1 to 3 times the steady-state current

Capacitive load 20 to 40 times the steady-state current

Transformer load 5 to 15 times the steady-state current

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POWE

READY

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National Instruments CFP-RLY-421 User Manual Page 8