Precision-digital PD6200 User Manual download pdf (Page 23)

Model PD6200 Analog Input Rate/Totalizer Instruction Manual

Switching Inductive Loads

The use of suppressors (snubbers) is strongly recommended when

switching inductive loads to prevent disrupting the microprocessor’s op-

eration. The suppressors also prolong the life of the relay contacts. Sup-

pression can be obtained with resistor-capacitor (RC) networks assem-

bled by the user or purchased as complete assemblies. Refer to the fol-

lowing circuits for RC network assembly and installation:

Figure 12: AC and DC Loads Protection

Choose R and C as follows:

R: 0.5 to 1  for each volt across the contacts

C: 0.5 to 1 µF for each amp through closed contacts

Notes:

1. Use capacitors rated for 250 VAC.

2. RC networks may affect load release time of solenoid loads. Check

to confirm proper operation.

3. Install the RC network at the meter's relay screw terminals. An RC

network may also be installed across the load. Experiment for best

results.

Figure 13: Low Voltage DC Loads Protection

RC Networks Available from Precision Digital

RC networks are available from Precision Digital and should be applied

to each relay contact switching an inductive load. Part number:

PDX6901.

Note:

Relays are de-rated to 1/14th HP (50 watts) with an inductive load.

Use a diode with a reverse

breakdown voltage two to

three times the circuit vol-

tage and forward current at

least as large as the load

current.

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Precision-digital PD6200 User Manual Page 23