Switching Inductive Loads; Figure 13. Ac And Dc Loads Protection; Figure 14. Low Voltage Dc Loads Protection - FlowLine DataView LI55 Instruction Manual

DataView™ LI55 Level Controller

Switching Inductive Loads

The use of suppressors (snubbers) is strongly recommended when switching
inductive loads to prevent disrupting the microprocessor's operation. The
suppressors also prolong the life of the relay contacts. Suppression can be
obtained with resistor-capacitor (RC) networks assembled by the user or
purchased as complete assemblies. Refer to the following circuits for RC network
assembly and installation:
Choose R and C as follows:
R: 0.5 to 1 Ω 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 14. Low Voltage DC Loads Protection

Note: Relays are de-rated to 1/14th HP (50 watts) with an inductive load.
MN301033 Rev B1
C
R

Figure 13. AC and DC Loads Protection

Instruction Manual
C
R
Use a diode with a reverse
breakdown voltage two to three
times the circuit voltage and
forward current at least as large
as the load current.
23