DJYVP Overall Screened Instrumentation Cable
DJYVP-300/500V
PE-insulated pairs under one copper braid screen, for analogue and digital runs of a single signal class.
Instrumentation & Signal Cable
Instrumentation cable carries the signal that the control system acts on, and its construction is defined by capacitance, crosstalk and shielding geometry rather than by current ra
Instrumentation cable carries the signal that the control system acts on, and its construction is defined by capacitance, crosstalk and shielding geometry rather than by current rating. Polyethylene insulation keeps mutual capacitance near 50–60 pF/m against 90–130 pF/m for a PVC pair, conductors are twisted into pairs with a short, controlled lay length so that an external field induces equal and opposite voltages in the two legs, and the screen is placed where the interference study says it belongs.
The DJ family used in China encodes that decision in the type designation: the position of the P tells you whether the braid sits over each pair, over the whole bundle, or over both. Voltcore builds the DJ range to GB/T with 1 to 24 pairs in 0.5–2.5 mm², and supplies the DIN VDE equivalents — RE-2Y(St)Y PiMF with DIN 47100 colour coding and blue sheath for intrinsically safe circuits — on the same production lines for European projects.
5 constructions in Instrumentation & Signal Cable
DJYPV Individual Pair Screened Instrumentation Cable
DJYPV-300/500V
A braid over every pair, so crosstalk between channels stops at the pair boundary.
DJYPVP Instrumentation Cable (Pair + Overall Screen)
DJYPVP-300/500V
The default specification when analogue, digital and switching channels share one cable.
RE-2Y(St)Y PiMF Instrumentation Cable
RE-2Y(St)Y-300/500V
The European equivalent of the DJ range: PE pairs, static screen, DIN 47100 identification.
RS-485 / Profibus / Modbus Bus Cable
BUS-485-120R
Impedance-controlled twisted pair for RS-485, Profibus DP and Modbus RTU segments.
Is individual pair shielding (PiMF) worth the extra cost?
An overall screen stops interference entering the cable. It does nothing about interference generated inside it: a 24 V DC solenoid circuit switched in the same bundle will induce a spike into an adjacent 4–20 mA pair, and no overall braid prevents that. Individual pair screens put a grounded barrier between the pairs, which is what PiMF — pairs in metal foil — exists to do.
The practical test is whether one cable carries mixed signal classes. A bundle that is entirely 4–20 mA loops, or entirely digital, is adequately served by an overall screen. The moment a switching circuit, a pulse train or a 100 mV thermocouple shares the sheath, specify individual screens and accept the larger diameter.
- Single signal class throughout: overall screen is enough (DJYVP).
- Mixed analogue and switching circuits in one cable: pair screens plus overall screen (DJYPVP).
- Millivolt signals such as thermocouples and strain gauges: always individually screened pairs.
- Each pair screen must be drained at one point only to avoid circulating current between the screens.
How do I keep a 4–20 mA loop inside its error budget?
A two-wire transmitter needs the loop supply to exceed the sum of the transmitter minimum operating voltage, the receiver burden and the voltage lost in the cable. A typical transmitter needs 12 V, a 250 Ω receiver drops 5 V at 20 mA, and the cable drops 2 × loop length × resistance per kilometre. Work the arithmetic on the return pair, not on one core.
At 1.5 mm² (12.1 Ω/km) a 1 000 m loop returns 24.2 Ω of cable, dropping 0.48 V at 20 mA — comfortable. At 0.5 mm² the same loop returns 72 Ω and drops 1.45 V, which still works but leaves little margin for a long run in a hot tray where resistance rises with temperature.
- Cable resistance rises about 0.4 % per K, so de-rate the loop at the maximum ambient temperature, not at 20 °C.
- Keep the total mutual capacitance of the pair below the transmitter's specified load, typically under 0.1 µF.
- Screen the pair and earth the screen at one end for a pure analogue loop to avoid a ground-loop current.
- Allow at least 5 V of headroom between the supply and the sum of transmitter, burden and cable drops.
What must a cable do in an intrinsically safe circuit?
In an Ex i installation the cable is part of the safety calculation, not just a conductor. The total capacitance and inductance of the loop — cable plus field device — must stay within the limits certified for the associated apparatus, so the cable datasheet has to state mutual capacitance and L/R ratio, not merely construction.
Identification and segregation matter as much as the numbers. Intrinsically safe circuits are identified by a light blue sheath and must be separated from non-IS circuits by at least 50 mm, by a grounded metal screen, or by an insulating divider, to prevent a fault transferring energy across.
- Light blue sheath to identify intrinsically safe circuits, per IEC 60079-14 installation practice.
- State mutual capacitance and inductance per kilometre so the designer can complete the entity calculation.
- Separate IS and non-IS cores by 50 mm or by an earthed metal barrier when they share a tray.
- Do not put IS and non-IS circuits in the same cable, even with individual screens.
Request pricing across Instrumentation & Signal Cable
Include cross-section, core count, voltage grade, route length and installation method — those five determine price more than anything else on the page.
- Engineer-reviewed before pricing
- Reference drawings issued with the quotation
- Free sample up to free sample up to 5 m