Technology
Delcon relays use pulse transformers to transfer switching energy across a galvanic barrier. Control-side electronics stay isolated from the load, improving safety and immunity to noise, surges and ground differences in demanding industrial installations.
How it works
1. Input signal
A PLC, sensor or switch presents the control command. The input section conditions the signal for reliable detection across cable lengths and voltage levels.
2. Pulse generator
Control logic converts the command into well-defined pulse packets optimized for magnetic coupling — not a continuous DC path across the barrier.
3. Pulse transformer
Energy crosses the isolation boundary as magnetic flux. There is no galvanic connection between input circuitry and the load side.
4. Output driver
The secondary side reconstructs pulses into strong gate or driver signals suited to the switched semiconductor and load type.
5. Isolated output
The load is switched with robust drive capability while remaining electrically isolated from the control world — reducing noise coupling and ground-loop issues.
Technical principle
The pulse transformer is the heart of Delcon relay electronics. It combines high isolation strength with efficient transfer of switching energy. Unlike optocoupler-based approaches that rely on LED–photodiode coupling and exhibit leakage and capacitive coupling, pulse transformer coupling minimizes parasitic paths that cause false triggering and misleading indication under noisy or long-cable conditions.
Together with purpose-designed driver stages, the result is predictable switching behavior for AC or DC loads, including demanding inductive applications.
Pulse transformer technology - operational principle
1. INPUT STAGE
Signal Conversion
Control signal ON/OFF
High-frequency pulse generator
2. ISOLATION BARRIER
Pulse Transformer Coupling
GALVANIC ISOLATION BARRIER
Magnetic coupling only - no optical path, no galvanic path
Reinforced isolation for safety-related and noisy plant environments
Low coupling capacitance for long I/O and sensor cables
No mechanical contacts, no contact wear
No LED-aging behavior as in optocouplers
3. OUTPUT STAGE
Power Switching
Decoder and output driver
Solid-state switching element
Key advantages
Low parasitic coupling keeps noisy environments, long runs and capacitive cables from turning into phantom turn-on events.
Robust drive characteristics suit solenoids, brakes, contactors and motor circuits where conventional SSR solutions often struggle.
Handles extreme inrush peaks reliably, ensuring stable switching without oversizing.
No mechanical contacts to wear out — ideal for high-cycle plant automation and maintenance-critical installations.
Technical specifications (typical)
Isolation voltage
4 kV RMS
Surge withstand
90 A / 20 ms
CMTI
High
Rated load current
AC: 240 VAC, 3 A (cos phi = 0...1)
DC: 380 VDC, 5 A
Operating temperature
-40 to +75 C
Standards alignment
IEC / UL design practices
Values depend on product series - confirm in the datasheet for your ordering code.
Typical applications
PLC & I/O modules
Solenoid & valve control
Brakes & clutches
Motors & contactors
Sensors & instrumentation
Technology comparison
Typical performance comparison in industrial switching applications. Exact behavior depends on model, load and installation.
| Feature / Phenomenon | Mechanical Relay | Opto-relay (SSR) | Delcon Relay |
|---|---|---|---|
| Noise immunity (long cables) | Poor to moderate | Poor | Excellent |
| Sensitivity to cable capacitance | Moderate | High | Low (Eliminated) |
| Switching Inductive DC Loads | Very Poor (Severe arcing) | Moderate | Excellent |
| High DC Voltage Switching | Limited (Arcing risk) | Varies (Voltage drops) | Superior (Up to 400V) |
| Leakage current (load circuit) | None | High (1-3 mA) | None / Negligible |
| dV/dt immunity (fast transients) | Good, but arcing | Limited | Superior |
| Arcing & Sparking | Constant (Wear/Risk) | None | None |
| Inrush current tolerance | Poor to moderate | Moderate | Good to excellent |
| Mechanical wear / Contact welding | Yes (High maintenance) | No | No |
| Operation with very low loads | Good | Poor to moderate | Good |
| Lifespan in harsh environments | Significantly reduced | Moderate | Extraordinarily long |
Discover how Delcon pulse transformer relays can improve safety, uptime and efficiency in your application.