Schneider Zelio vs ABB CR: Interface Relay Comparison
How do Schneider Zelio and ABB CR interface relays compare? Both families cover the same job in a control panel — a DIN-rail plug-in relay on a screw or push-in socket that isolates a PLC or DCS output and switches a load-side circuit rated for several amps at 250 VAC, built to IEC 61810 and IEC 60947-5-1 — but the two ranges split at slim-module width, socket keying, and the coil and contact break points on offer. Get the socket-relay pairing wrong and a panel either wastes DIN-rail space on an oversized module or under-rates a contact for the load it drives. This article compares contact arrangements, coil voltage options, coil-suppression modules, socket and terminal systems, and slim relay density across Schneider's RXM/RSB/RSL/RPM lineup and ABB's CR-P/CR-M/CR-U range.
Zelio vs CR: What Each Range Covers
Schneider groups its interface relays under the Zelio and Harmony names. RXM is the general-purpose miniature plug-in relay, offered in 2 CO and 4 CO versions on RXZE sockets, with clip-in RXM LED and suppression modules. RSB is the dedicated interface relay — 1 CO or 2 CO — sold with integral socket options for a smaller footprint per channel. RSL is the slim interface relay, about 6 mm wide, built for high channel density next to a PLC rack, with push-in terminal variants. RPM and RUMC cover power plug-in relays for higher contact currents, and RXG/RUMF fill in adjacent variants. Coil options run mainly 24 VDC with AC alternatives.
ABB structures its range around the CR prefix. CR-P is the pluggable interface relay, PCB or DIN mount, 1 to 4 CO, on CR-P sockets. CR-M is the industrial plug-in relay for higher current work, 2 to 4 CO, on CR-M sockets. CR-U is a universal plug-in range that spans both duties. LED indication and coil-suppression modules clip into the socket on both CR-P and CR-M, and both offer screw or push-in terminal versions. ABB also carries the older R600 interface family for panels still being maintained on legacy stock.
See the full range breakdowns in the interface relay basics guide and the types of interface relays article, or start from the interface and coupling relay engineering guide for the full picture.
Contact Arrangements and Current Ratings
Both ranges span 1 CO up to 4 CO change-over contacts, moving from a single switched circuit to four independent loads on one relay. Contact ratings are split by current type: an AC1 rating (resistive AC load, roughly 6 A class at 250 VAC on the smaller interface types) and a separate DC rating that falls sharply as voltage climbs, because a DC circuit has no natural zero-crossing to help quench the arc. Neither Schneider's RXM/RSB nor ABB's CR-P/CR-M publish one universal number across every coil-voltage and contact-material variant, so treat any current figure as a starting point to confirm against the specific model, not a fixed constant across the family.
What we see in the field: panels spec'd against a datasheet peak current without checking the AC1 vs DC1 split end up with a relay that trips on load, not on a fault. If the load is a contactor coil or a solenoid, that's a DC1 number, and it's the one that matters, not the AC headline figure.
Read more on the contact side in relay contact configurations from SPDT to 4PDT.
Coil Voltages and Suppression Modules
24 VDC is the default coil voltage on both ranges for PLC-driven panels, since it matches the 24 VDC field supply already in the cabinet. Both Zelio and CR relays also come in 24/48/110 VAC and 230 VAC coil options for panels wired to line voltage control circuits. Pull-in and drop-out voltages are specified as a percentage of the rated coil voltage, and coil power sits in the few-hundred-mW to roughly 1 W range depending on the model.
Formula: Relay coil power and switching thresholds — Source: IEC 61810, general relay characteristics
Pcoil = Un × Icoil; Upull-in ≈ 0.8 × Un; Udrop-out ≈ 0.1–0.3 × Un
| Symbol | Description | Unit |
|---|---|---|
| Pcoil | Coil power consumption | W |
| Un | Rated coil voltage | V |
| Icoil | Coil current at rated voltage | A |
| Upull-in | Minimum voltage that reliably energizes the relay | V |
| Udrop-out | Voltage below which the relay releases | V |
Both brands build coil suppression into a clip-in module rather than a fixed part of the relay: a freewheel diode for DC coils, or an RC network or varistor for AC coils. The diode is polarity-sensitive and clamps the coil's collapse voltage spike on de-energization — skip it on a DC coil driven by a PLC transistor output and the output stage fails, sometimes not on the first cycle, but eventually. This depends on whether the PLC output sinks or sources current, which decides which way the diode has to be wired.
More detail in relay coil voltage options explained and coil suppression methods for diode, RC and varistor.
Socket Systems and Terminal Options
The socket, not the relay, carries the terminal rating and the retaining mechanism, so the socket choice matters as much as the relay choice. Screw terminals are the familiar option and can be re-torqued during commissioning; push-in (spring) terminals wire faster and hold under vibration without a periodic re-torque check. Schneider offers screw and push-in variants across RXZE, RSB integral sockets, and RSL slim sockets. ABB offers the same screw-or-push-in choice on CR-P and CR-M sockets. Neither brand's sockets accept the other brand's relay — the pin spacing, keying, and LED/suppression module slot are brand-specific, so a socket swap mid-project means a full relay swap too.
Always check the socket rating printed on the socket itself, not just the relay's datasheet figure, since a lower-rated socket becomes the limiting component in the pair.
See the mechanics of the pairing in how the plug-in relay and socket system works.
Slim Interface Relays for High-Density Panels
Where channel count matters more than contact current, both brands shrink the module width. Schneider's RSL is built around a roughly 6 mm module for placing dozens of interface points next to a PLC I/O rack without eating the whole DIN rail. ABB's slim CR-P variants target the same 6–6.2 mm class for the same reason: one relay per digital output, packed tight. Push-in terminal options exist on both slim lines, which matters more here than on the general-purpose RXM/CR-U relays, because a slim panel with 40+ channels wired on screw terminals is a slow commissioning day.
These slim relays sit at the isolation-and-amplification layer between the PLC card and the field device — each channel takes a signal-level output and hands off a load-level contact. Background on that role is in PLC interface relays for isolating and amplifying I/O.
Which Range Fits Your Application?
Contact count, coil voltage, and terminal type narrow the choice fast; the table below lines up the two ranges on the criteria that actually drive a purchase order.
| Criteria | Schneider Zelio (RXM/RSB/RSL/RPM) | ABB CR range (CR-P/CR-M/CR-U) |
|---|---|---|
| General-purpose plug-in | RXM, 2 CO / 4 CO | CR-U, universal 1–4 CO |
| Dedicated interface relay | RSB, 1 CO / 2 CO with integral socket | CR-P, 1–4 CO on CR-P socket |
| Higher-current power plug-in | RPM / RUMC | CR-M, 2–4 CO |
| Slim high-density module | RSL, ≈6 mm | CR-P slim, ≈6–6.2 mm |
| Terminal options | Screw and push-in | Screw and push-in |
| Governing standards | IEC 61810 / IEC 60947-5-1 | IEC 61810 / IEC 60947-5-1 |
If the project already runs Schneider contactors and Zelio logic relays, staying in the Zelio family keeps sockets, spares, and LED modules common across the panel. The same logic runs the other way for an ABB-standardized panel with CR-P or CR-M already on the BOM. For a mixed-brand panel, match on the criteria in the table — contact count, coil voltage, and terminal style — rather than on brand alone, and check contact and coil compatibility against how a contactor differs from a relay when the load is a contactor coil.
For selection steps against specific PLC output types, see how to select an interface relay for PLC outputs. Browse stocked options in interface and control relays and pair with contactors where the relay is driving a contactor coil.
Frequently Asked Questions
Are Schneider Zelio and ABB CR interface relays interchangeable?
No. The relay and socket are matched pairs within a brand — pin spacing, keying, and the LED/suppression module slot are brand-specific. A Zelio relay will not seat in a CR-P socket, and the reverse is also true.
What is the difference between Schneider RXM and RSB relays?
RXM is the general-purpose miniature plug-in relay in 2 CO or 4 CO on a separate RXZE socket. RSB is a dedicated interface relay in 1 CO or 2 CO, often sold with an integral socket for a smaller per-channel footprint.
Which coil voltage should I choose for a PLC-driven panel?
24 VDC is standard when the relay is driven directly from a PLC transistor output or a 24 VDC field supply. AC coil options (24/48/110/230 VAC) apply when the control circuit itself runs on line voltage rather than a DC logic supply.
Should I choose push-in or screw terminals on the socket?
Push-in terminals wire faster and resist loosening under vibration, which suits high-channel-count or machine-mounted panels. Screw terminals stay common where periodic re-torque checks are part of the maintenance routine or where field technicians expect them.
Can I mix relay and socket brands on the same DIN rail?
Physically yes, since both brands mount to standard DIN rail, but each relay still needs its own matching socket. Mixing brands adds spare-parts variety without an isolation or rating benefit, so most panels standardize on one brand's socket family per section.
Does a slim interface relay switch a smaller load than a standard one?
Generally yes. Slim relays (RSL, CR-P slim) are built for I/O density next to a PLC rack, and their contact ratings sit at the lower end of the family compared to the general-purpose or power plug-in models.
Conclusion
Schneider's Zelio range and ABB's CR range solve the same interfacing problem with a similar structure: a general-purpose relay, a dedicated low-count interface relay, a slim high-density module, and a higher-current power plug-in variant, each on a brand-specific socket with clip-in LED and suppression modules. The real decision points are contact count against the load, coil voltage against the control supply, screw versus push-in against the wiring routine, and — once those match — which brand's socket family is already standardized in the panel. Start from the electromechanical vs solid-state interface relay comparison if the application calls for high-cycle switching instead of a standard electromechanical relay, and check thermal overload relays when the panel also needs motor protection alongside signal interfacing.
