National Instruments CFP-RLY-421 用户手册

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.

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.

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