Schneider Electric CAD50BD TeSys D Relay 5NO 24V DC

CAD50BD TeSys D control relay: what the part number tells you

The CAD50BD is a Schneider Electric TeSys D control relay: TeSys D control relay, 5 NO, up to 690 V, 24 V DC standard coil. In plain terms it is a contactor-style relay with five normally open contacts, designed for control circuits rather than motor power, and its coil is rated 24 V DC. Seven Star LLC supplies the CAD50BD in Oman and the GCC as an independent supplier based in Muscat.

Reading the code against the datasheet: CAD is the TeSys D control relay series, 50 gives the 5 NO contact arrangement (five poles in both cases), and the ending BD stands for the 24 V DC coil that the datasheet lists for this reference. Neighbouring references differ only in the coil voltage or type, so the complete code decides whether the relay will fit your control supply.

Technical specifications of the CAD50BD

Coil, operating window and supply sizing for the CAD50BD

The coil is the one part that distinguishes the CAD50BD from its siblings, so it deserves the closest reading.

The 24 V DC coil is the everyday choice for control panels that already carry a 24 V supply for PLC inputs, sensors and indicator lamps. The datasheet lists 5.4 W for this standard-consumption coil, which is about 0.23 A when the relay is held in. That is more than a typical transistor output channel will deliver on its own, so the coil is usually driven through an interposing element or from a relay or output rated for the current.

The operational window of 0.7 to 1.25 Uc corresponds to roughly 16.8 to 30 V on this coil, which covers the ripple and sag of an ordinary unregulated or lightly loaded 24 V supply, and the drop-out band of 0.1 to 0.25 Uc, about 2.4 to 6 V, means the relay releases cleanly when the supply is removed. Choose the standard coil when the supply is generous and fast operation matters; the low-consumption alternative with suffix BL trades speed and power for a smaller load on the supply.

Calculated from the datasheet, the 24 V DC coil of the CAD50BD has an operational window of 16.8 to 30 V (0.7 to 1.25 Uc), and it drops out at 2.4 to 6 V (0.1 to 0.25 Uc). The datasheet gives 5.4 W for inrush and for hold-in, which corresponds to about 225 mA at pull-in and when held in at the nominal voltage. These are indicative figures worked out from the stated power and voltage, and they are meant for supply sizing, not as guaranteed current ratings.

Contact arrangement of the CAD50BD: five normally open contacts

The 5 NO configuration is the version for pure signal multiplication. With no normally closed contacts, all five poles close when the coil is energised, so a single command can start, indicate and permit several circuits at once. The datasheet lists operating times only for the normally open contacts, as there are no normally closed contacts to describe.

Choose it when a single initiating contact, for example a PLC output or a protection relay trip contact, has to be repeated on five independent circuits: alarm annunciation, a shutdown loop, a remote indication, an interlock to another panel and a counter or logger. If any of those circuits needs a contact that opens when the relay operates, the 3 NO + 2 NC member of the family is the right choice instead.

Contact data from the datasheet apply to all five poles: 10 A conventional thermal current at 60 °C, utilisation categories AC-15, AC-14 and DC-13, a rated operational voltage up to 690 V AC, and a minimum switching capability of 17 V and 5 mA, which makes the contacts suitable for low-level signals as well as for 24 V PLC inputs.

Where the CAD50BD sits in the CAD50 family

The CAD50BD is one member of a family of TeSys D control relays that share the housing, the contact data and the mounting. Only the coil voltage and type change from one reference to the next, together with the contact arrangement: the CAD32 series is 3 NO + 2 NC and the CAD50 series is 5 NO. The table lists the CAD50 references we are asked for most.

If the supply is not in the table, ask us; the CAD32 series has the other contact arrangement. AC-coil versions are 84 mm deep and DC-coil versions 93 mm, which matters in a shallow enclosure.

Selection checklist for the CAD50BD

• Coil: 24 V DC, confirmed from the supply drawing or the nameplate of the relay being replaced.
• Contacts: five normally open contacts, matched to the interlock and signalling circuits.
• Supply sizing: about 225 mA continuously, because the datasheet gives the same power for inrush and hold-in (derived figure).
• Window: operates within 16.8 to 30 V (0.7 to 1.25 Uc) and releases at 2.4 to 6 V (0.1 to 0.25 Uc).
• Contact load of the CAD50BD: 10 A thermal, AC-15, AC-14 or DC-13 duties; use a contactor for motor-power loads.
• Space: 77 mm high, 45 mm wide and 93 mm deep.
• Environment: operation up to 60 °C, up to 70 °C with derating; storage -60 to 80 °C.

Mounting, wiring and service life of the CAD50BD

Mount the CAD50BD on a 35 mm DIN rail or on a plate; the datasheet lists both. It measures 77 mm x 45 mm x 93 mm and weighs 0.58 kg, so allow space for the wires to bend at the terminals and for air to circulate around the housing. Tighten the screw-clamp terminals to 1.7 N.m with a Philips No 2, Pozidriv No 2 or 6 mm flat screwdriver, and do not exceed the cable sizes of 1 to 4 mm² per terminal listed in the datasheet.

Commissioning is simple: energise the coil at nominal voltage, verify that all five poles move together, and check the contact action with a meter before connecting the field loads. The mechanical durability is 30 million cycles and the maximum operating rate is 180 cycles per minute, so in normal control duty there is no routine wear item to schedule. In a dusty site, clean the panel and check terminal tightness during planned shutdowns, because loose terminals, more often than the relay itself, cause intermittent faults.

Where the CAD50BD is used in Oman and the GCC

In Oman and the GCC a low-voltage DC coil is most often found in packaged skids, compressor and generator control panels, fire-and-gas interface cabinets and remote telemetry shelters, where a 12, 24 or 48 V battery-backed supply keeps the controls alive through a mains failure. In these cabinets the relay repeats a PLC or safety-system signal to field circuits, and the five poles save space compared with a bank of small plug-in relays.

For the CAD50BD, that means five normally open contacts from one 24 V DC command, sitting next to LC1D contactors of the same TeSys D family on the same rail.

Information to send with an RFQ for the CAD50BD

• Full reference CAD50BD and the quantity
• The coil voltage and type seen on the supply drawing or on the old relay nameplate
• The load or circuit each contact will switch (voltage, current, signal level)
• Panel or machine the relay must fit, and whether it is a spare, a replacement or a new installation
• Delivery location in Oman or the GCC and the date required

Documents and quotation

A datasheet for this product is attached on this page. It lists the electrical, mechanical and environmental data summarised above, and it is worth reading beside the panel drawing before you order.

Send us the part number, quantity and application and we will confirm availability and a quotation. Seven Star LLC is an independent supplier in Muscat and is not affiliated with the manufacturer.