+24 VDC
–24 VDC
Module Relay Contact
–324 VDC
+24 VDC
+24 VDC
–24 VDC
Module Relay Contact
–42 VDC
+24 VDC
Chapter 3: I/O Wiring and Specifications
3–10
DL205 Installation and I/O Manual, 2nd Edition
Transient Voltage Suppressors (TVS or transorb) provide the best surge and transient
suppression of AC and DC powered coils, providing the fastest response with the smallest
overshoot.
Metal Oxide Varistors (MOV) provide the next best surge and transient suppression of AC
and DC powered coils.
For example, the waveform in the figure below shows the energy released when opening a
contact switching a 24 VDC solenoid. Notice the large voltage spike.
This figure shows the same circuit with a transorb (TVS) across the coil. Notice that
the voltage spike is significantly reduced.
Use the following table to help select a TVS or MOV suppressor for your application based
on the inductive load voltage.
3
+24 VDC
–24 VDC
Module Relay Contact
–324 VDC
+24 VDC
+24 VDC
–24 VDC
Module Relay Contact
–42 VDC
+24 VDC
Vendor / Catalog
Suppressor Types
Inductive Load Voltage
Part Number
AutomationDirect
Transient Voltage
Suppressors
www.automationdirect.com
8–channel TVS
8–channel TVS
24 VDC
110 VAC
ZL–TD8–24
ZL–TD8–120
General Instrument Transient Voltage
Suppressors and LiteOn Diodes; from
Digi-Key Catalog; www.digikey.com;
Phone: 1-800-344-4539
TVS, MOV
TVS, MOV
TVS
Diode
110/120 VAC
220/240 VAC
12/24 VDC or VAC
12/24 VDC or VAC
Check Digi-Key Corp.
catalog or website