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National Instruments Corp.

5

FP-RLY-422

The maximum switching capacity of each relay is 3 A up to 
250 VAC or 35 VDC. To switch greater DC voltages, refer to 
Figure 4.

Figure 4.  

Maximum Current vs. DC Volts

Contact Protection for Inductive Loads

When inductive loads are connected to the relays, a large 
counter-electromotive force may occur at relay switching time 
because of the energy stored in the inductive load. These flyback 
voltages can severely damage the relay contacts and greatly 
shorten the life of the relay.

It is best to limit these flyback voltages at your inductive load by 
installing, across your inductive load, a flyback diode for DC loads 
or a metal oxide varistor (MOV) for AC loads. Refer to the next 
section, 

Guidelines for Selecting Contact Protection Circuits

, for 

more information.

In addition, the FP-RLY-422 contains its own internal protection 
MOV to prevent excessively high voltage from being applied 
across the contacts. Each channel contains two MOVs: one 
between N.Closed and I.Com and one between N.Open and I.Com. 
However, National Instruments still recommends the use of a 
protection circuit across your inductive load.

20

0

40

60

DC Volts

Current

(Amps)

80

100 120

.5

1

1.5

2

2.5

3

Safe Operating

Region

Содержание FP-RLY-422

Страница 1: ... particular FieldPoint network module you are using with the FP RLY 422 Features The FP RLY 422 is a FieldPoint relay output module with the following features Four Single Pole Double Throw SPDT relay channels Switching capacity 3 A at 35 VDC or 250 VAC On Off LED indicators Hot plug and play operation 3 000 V input to output isolation Double insulated for 250 V safe working voltage 40 to 70 C ope...

Страница 2: ...llation Diagram Field Wiring The terminal base has connections for each of the four relay channels and an external supply to power field devices Each relay channel of the FP RLY 422 has four terminals one N Open Normally Open two I Com Isolated Common and one N Closed Normally Closed The external supply is not needed for the internal operation of the FP RLY 422 however you may connect an external ...

Страница 3: ...igure 2 Basic Field Connection Table 1 Terminal Assignments Channel Terminal Numbers N Open I Com N Closed VSUP COM 0 1 2 3 4 17 18 19 20 1 5 6 7 8 21 22 23 24 2 9 10 11 12 25 26 27 28 3 13 14 15 16 29 30 31 32 a Total Current Less Than 5 Amps b Total Current Greater Than 5 Amps V C Vsup N Open I Com I Com Vsup N Closed COM Load Load N Closed I Com N Open I Com Load Load ...

Страница 4: ...connect I Com to N Open Choose the impedance of the loads so that the current switched by any one channel is no more than 3 A Each relay can be controlled separately without affecting the others or all relays can change states at the same time There is an effective resistance of 100 mΩ between I Com and N Closed or N Open This resistance will cause a voltage drop For example if the current is 3 A ...

Страница 5: ...relay It is best to limit these flyback voltages at your inductive load by installing across your inductive load a flyback diode for DC loads or a metal oxide varistor MOV for AC loads Refer to the next section Guidelines for Selecting Contact Protection Circuits for more information In addition the FP RLY 422 contains its own internal protection MOV to prevent excessively high voltage from being ...

Страница 6: ...xamine the circuit you are planning to use Diode and Zener Diode Circuit Diode Circuit 1 This section has been reprinted with permission from American Zettler Inc Diagram Notes Use in DC applications only Use when diode circuit causes too long release time Use zener diode with zener voltage about equal to power supply voltage Diagram Notes Use in DC applications only Compared to RC type circuit de...

Страница 7: ...e Diagram Notes Circuit A is suitable for AC or DC applications but if used with AC voltage impedance of the load should be smaller than the CR circuit s Do not utilize for timer loads as leakage current can cause faulty operations Circuit B is suitable for AC or DC If the load is a relay or solenoid release times lengthen Effective when connected to both contacts power supply voltage across the l...

Страница 8: ...ion the green READY indicator lights and the FP RLY 422 is in its normal operating mode In addition to the green POWER and READY indicators each channel has two green output state indicators labeled Table 2 Typical Load Types and In Rush Currents 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 stead...

Страница 9: ...ulation between hazardous voltages and any human accessible parts or circuits You should never attempt to use any isolation product between human accessible parts such as DIN rails or monitoring stations and circuits that may be at hazardous potentials under normal conditions unless the product is specifically designed as the FP RLY 422 is for such an application Even when a product like the FP RL...

Страница 10: ...ecifications The following specifications are typical for the range 40 to 70 C unless otherwise noted Input Characteristics Number of channels 4 Relay type 1 Form C SPDT Nonlatching Maximum Switching Capacity Resistive Load AC 3 A at 250 VAC DC 3 A at 35 VDC 2 A at 40 VDC 1 A at 55 VDC 0 4 A at 120 VDC Minimum switching voltage 10 mA at 5 VDC On resistance 100 mΩ Off state leakage 0 3 µA at 250 VA...

Страница 11: ... indicators 8 green output state indicators Weight 182 g 6 4 oz Power Requirements Power from network module 1000 mW Environment Operating temperature 40 to 70 C Storage temperature 55 to 100 C Relative humidity 5 to 90 noncondensing CE Mark Compliance This product meets applicable EU directive s as follows Safety isolation EN 61010 double insulation for 250 Vrms working isolation installation cat...

Страница 12: ...l Dimensions Figure 6 shows the mechanical dimensions of the FP RLY 422 installed onto a terminal base Dimensions are given in inches millimeters Figure 6 Mechanical Dimensions 4 31 109 5 3 60 91 44 4 22 107 19 ...

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