ZeroDT
Non-degrading surge protection for instrument loops, control panels and Ethernet.
ZeroDT builds surge protection for the signal, network and power wiring that ties a plant's instruments to its control system. The technology is the point: ZeroDT uses silicon avalanche suppression diodes rather than the gas discharge tubes and metal oxide varistors common in this category, and its case is that those parts wear a little with every surge while its own do not, so a protector gives the same protection years in as on the day it went in. The line runs from protectors small enough to sit inside a transmitter housing, through DIN-rail modules for the panel, to cast aluminum conduit enclosures for hazardous areas. Products are made in the U.S.A., and ZeroDT lists UL 497B and UL 121201 certifications. Rust distributes ZeroDT, so tell us the voltage, the number of loops and where the protector has to live, and we will match the model.
What we carry
Pick the group you need.
Small enough to mount inside the device or a small housing, at the transmitter or valve end of the loop.
12-1 and 12-2
12 Vdc protectors, 18 Vdc maximum continuous voltage. The 12-1 covers a single loop or 2-wire circuit; the 12-2 covers 2 loops or 4 wires. UL Listed for ordinary and Class 1, Div 2 locations.
Use it whenUse these on 12 V field devices where the protector has to fit inside the instrument housing rather than a separate box.
24-1 and 24-2
24 Vdc protectors. The 24-1 covers a single loop or 2-wire circuit; the 24-2 covers 2 loops or 4 wires. UL Listed for ordinary and Class 1, Div 2 locations.
Use it whenThe everyday choice for 4-20 mA transmitters and automated valves on 24 V loops. Pick the 24-2 when a device brings two pairs to protect.
48-1 and 120-1
Single-loop protectors for 48 Vdc, and for up to 120 Vac or 170 Vdc.
Use it whenUse these when the field circuit runs above 24 V, such as a 48 V supply or a 120 V AC solenoid or switch circuit.
The same protection, prewired in a Type 4X cast aluminum conduit enclosure that ZeroDT describes as designed for Class 1, Div 1 locations. 24 Vdc.
FM-2 and FM-4
Conduit enclosures built around the 24-2 protector: the FM-2 protects 1 loop (2 wires), the FM-4 protects 2 loops (4 wires). Terminal block wiring, two 3/4 in NPT conduit openings.
Use it whenUse these at a field instrument in a classified area where the protector cannot go inside the device itself.
S-4
An I/O-24 module in a cast aluminum conduit enclosure, protecting 2 loops (4 wires) with each line protected independently. Three 3/4 in NPT openings.
Use it whenUse it to protect both the power input and the output signals of a field device from one enclosure.
FM-8 and FM-12
Larger conduit enclosures with I/O-24 modules on DIN rail: the FM-8 protects 4 loops (8 wires), the FM-12 protects 6 loops (12 wires).
Use it whenUse these at a field junction where several loops come together, such as a wellhead, a skid or a remote I/O point.
DIN-rail modules for the control panel end of the wiring.
I/O-24
ZeroDT's most popular product: a DIN-rail module with 4 in and 4 out lugs for 4-20 mA loops, discrete and pulsed I/O, RS-485/422/232, DeviceNet, FOUNDATION Fieldbus, PROFIBUS PA and low-voltage DC power. 36 Vdc maximum continuous voltage. UL Listed for ordinary and Class 1, Div 2 locations.
Use it whenStart here for signal wiring entering a PLC, RTU or DCS cabinet. One module covers most low-voltage I/O and fieldbus types.
DC-24
DIN-rail protector for 24 Vdc or 24 Vac power, shunt or series connected, with a 15 A series rating.
Use it whenUse it on the 24 V supply feeding the panel's instruments and I/O, so a surge on the power side does not reach the electronics.
P120-20
ZeroDT's most powerful 120 VAC protector, on 35 mm DIN rail. UL 1449 5th Edition Type 2CA, UL 121201 Class I, Div 2, a red replace indicator and Form C contacts for remote monitoring. Rated -40 to +70 C.
Use it whenUse it on the 120 VAC feed into an industrial control panel. The dry contacts let the control system alarm when the unit needs replacing.
In-line protection for networked devices.
GB-1 and GB-2
Series-connected RJ-45 protectors for 10/100/1000 BASE-T Ethernet, all 8 pins protected, low capacitance so data rates are unaffected. The GB-1 protects one line, the GB-2 two. Listed for ordinary and Class 1, Div 2 locations.
Use it whenUse these on Ethernet runs to cameras, radios, remote I/O and anything else on the plant network that leaves the building or crosses the yard.
Cross-references & replacements
Replacing an existing ZeroDT product, or cross-referencing from another manufacturer? Send the old part number or a photo of the nameplate. Cross-references and sizing are at no charge, and we’d rather tell you an equivalent won’t work than sell you one that doesn’t.
Send a part number or a printProduct family information on this page was taken from zerodowntime.net and last verified . Specifications and model availability are the manufacturer’s and can change. We confirm current details when we quote.
Industries served
Related lines
Availability varies by line and location. Manufacturer agreements set where we can sell each line. Tell us where the project is and we’ll confirm what we can supply — or point you to the right source if it isn’t us.