Schneider Electric CAD50FD TeSys D Relay 5NO 110V DC

CAD50FD: a relay with five normally open contacts for 110 V DC control circuits

If you are replacing or specifying a 110 V DC control relay with five normally open contacts, the CAD50FD is the Schneider Electric TeSys Deca reference to look at. Its datasheet title reads: TeSys D control relay – 5 NO – up to 690 V – 110 V DC standard coil. Seven Star LLC supplies the CAD50FD in Oman and the GCC as an independent supplier based in Muscat.

How the reference breaks down: CAD means a TeSys Deca control relay, 50 fixes the contacts at five normally open contacts, and FD fixes the coil at 110 V DC. Because the other family members share the same housing, an error in the last two characters is the most common cause of a relay that arrives and does not suit the panel.

Technical data of the CAD50FD at a glance

Field use of the CAD50FD in the Gulf

A 110, 125 or 220 V DC coil is a substation and power-plant part. In the utilities, desalination plants and large industrial sites of the region, the station battery feeds protection and control, and a multiplying relay of this kind repeats trip, alarm and interlock signals inside switchgear panels and relay rooms. It is a natural spare for outage planning, because panel relays at that voltage are hard to buy quickly when a shutdown is under way.

The environment in a switchgear room is usually air-conditioned but not immaculate: fine dust gets in during maintenance, and humidity rises when air handling fails. The relay carries a TH protective treatment and a front-face rating of IP2X per the datasheet, which is a finger-safe, not a dust-tight, rating, so panel doors and filters remain the first line of defence.

For the CAD50FD, that means five normally open contacts from one 110 V DC command, sitting next to LC1D contactors of the same TeSys D family on the same rail.

Contact block of the CAD50FD

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.

Coil data and timing of the CAD50FD

The coil is the one part that distinguishes the CAD50FD from its siblings, so it deserves the closest reading.

A 110 V DC coil is typical of switchgear and substation control, where a station battery supplies protection relays, trip coils and indication. The CAD relay is then used as a multiplying or interposing relay: one contact from a protection device drives the coil, and the five poles repeat the signal to alarm, interlock, trip and indication circuits. The datasheet lists 5.4 W, about 49 mA at 110 V, so the load on the battery system is small.

The wide band of 0.7 to 1.25 Uc corresponds to roughly 77 to 137.5 V, which is important on a battery system that sags under heavy trip load and rises during boost charge. At the low end the relay still pulls in; at the high end it is still within its limit. A drop-out band of 0.1 to 0.25 Uc, about 11 to 27.5 V, stops the relay from hanging on in a circuit with leakage or a long cable. As always with DC coils, fit suppression across the coil if the device driving it is a delicate contact.

The datasheet gives operating times of 53 to 72 ms coil energisation and NO closing, 16 to 24 ms coil de-energisation and NO opening. The DC coil closes in 53 to 72 ms and opens in 16 to 24 ms, with a time constant of 28 ms, which is slower than an AC coil and should be kept in mind in tight timing circuits.

Installing and keeping the CAD50FD in service

Fit the relay in an enclosure with the front face reachable for inspection: the datasheet quotes IP2X at the front face, which protects against finger contact but not against dust. The weight of 0.58 kg is modest, so the relay is held securely by its rail clip, but plate mounting is preferable on machines with strong vibration. The datasheet lists vibration resistance of 2 Gn open and 4 Gn closed (5 to 300 Hz) and shock resistance of 10 Gn open and 15 Gn closed for 11 ms.

For spares planning, the CAD50FD is a good candidate for a stocked spare because it is physically identical to its siblings and the coil is the only part that differs. Mark the coil voltage clearly on the terminal block door or on the panel diagram, test it after any control-supply change, and keep a record of the coil code. The datasheet gives an 18-month warranty from the manufacturer, which applies to the product as supplied by its own channel.

Family table including the CAD50FD

The CAD50FD 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.

What to confirm before you buy the CAD50FD

• Coil: 110 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 49.1 mA continuously, because the datasheet gives the same power for inrush and hold-in (derived figure).
• Window: operates within 77 to 138 V (0.7 to 1.25 Uc) and releases at 11 to 27.5 V (0.1 to 0.25 Uc).
• Contact load of the CAD50FD: 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.

Quotation details we need for the CAD50FD

• Delivery location in Oman or the GCC and the date required
• Panel or machine the relay must fit, and whether it is a spare, a replacement or a new installation
• The load or circuit each contact will switch (voltage, current, signal level)
• The coil voltage and type seen on the supply drawing or on the old relay nameplate
• Full reference CAD50FD and the quantity

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.