Relay Selection

Here are some other relays & optocouplers we have in stock....

DIN Rail Mounted Electrical Relays

Function of Relays

Relays use an input voltage (on one circuit) to open or close one or more contacts (on a separate circuit). This allows the input circuit to operate at a different voltage than the output circuit. Or, it may be used to isolate the two circuits to prevent electromagnetic surges to be transmitted from one side to the other. This second application is called "signal isolation"?.

Types of Contacts

The secondary (or switched) circuits are controlled by contacts. These contacts are usually a pair of gold-plated or silver-plated copper discs that connect and disconnect to allow the secondary circuit to be interrupted or completed. These are referred to as "mechanical"? contacts. Contacts of this type may exhibit a property called "contact bounce"? where the contacts may close, then open briefly, and then close again. Because mechanical relays must physically move the contacts from open to closed or closed to open, there is a time delay between the input request and the output response. The larger the contact size is the large the delay will generally be. This is also determined by the size of the spring and electrical coil on the relay. An alternative to these types of contacts are semiconductor contacts.

Relay Construction Styles

Several options are available for relay construction styles:

• A miniature relay in a completely enclosed housing that looks like a terminal block
• A miniature relay that can be plugged into a housing that looks like a terminal block
• A completely enclosed relay with mounting feet for DIN rail mounting
• A relay that is permanently mounted on a printed circuit board. This PCB has mounting feet for DIN rail mounting
• A relay that can be plugged into a printed circuit board. This PCB has mounting feet for DIN rail mounting.

Pluggable versions offer the flexibility of changing the electromechanical nature of the relay after the equipment has been installed. This also provides easier maintenance in the event of relay failure.

Contact Designations

There is a universally accepted set of abbreviations for the number and function of relay output contacts. These are:

• (S) = Single
• (D) = Double
• (T) = Throw
• (P) = Pole
• (NO) = Normally Open
• (NC) = Normally Closed

If powering the input circuit will cause the output contacts to close, the output contacts will be referred to as "NO or Normally Open"?. This is the state of the contacts when there is no power applied to the input circuit. Normally Closed contacts are just the opposite.

If a relay has one pair of output contacts, they will be "Single Throw"?. Is possible, however, to connect a single output circuit to one contact by default and change it to another contact when the input is powered. This is known as "Double Throw"? or a change-over circuit.

There is virtually no limit on the number of output contacts that a relay may have. But, using the above abbreviations, you can easily determine the number and types of output contacts that have been specified for a relay. For example, the designation, SPDT, can be read as "Single-Pole, Double Throw"?. This means that there is one contact (the single pole) and it is a change-over contact (the double throw).

Contact Rating

The output contacts will have a voltage and current rating. Very high voltages will cause the electricity to arc across the contacts and burn (or oxidize) them. Contacts rated for very high voltages will generally have gold-plated contacts, the contact size will be much larger, and the contact housing may even be maintained in a vacuum to reduce oxidation.

The output contact current rating is related to the size of the conductors that used in the construction of the relay. The designer should choose a relay with output contacts that have sufficient voltage and current rating for the application.

Open Fixed

For applications that do not require the module to be fully enclosed. Weidmuller offers an open style (RS) relay. All of these products include a combi-foot which allows mounting on either TS 32 or TS 35 mounting rail. In addition, they feature LED power-on indication and pre-marked wire terminations. The open fixed version incorporates a relay or optocoupler that is soldered into the module, and therefore is not removable. This guarantees that the relay or optocoupler is makin a solid electrical connection but the entire module must be discarded if component replacement is required.

PLUGSERIES Relays

The amazing PlugSeries Relays provides a compact, rugged, and reliable relay package that is DIN-Rail mountable. The convenient lever helps remove the modular relay from the base. But what is truly unusual is that the single-pole versions can handle up to 16 Amps of continuous current in a 15.3mm wide package! And check out the price -- talk about an economical and exceptional value. Most of these relays include LED indication. Control voltages range from 24V to 230V. And, this series is available in both a screw and cage clamp version and a spring-tension clamp version.

This is a modular system including:

• relay socket for rail mounting
• LED indicator
• Retaining (Extraction) Clip
• Plug-in Relay

Below is dimensional information and wiring information for the PRS PlugSeries Relay product line. Note that these relays provide the ability for one or more plug-in jumpers (or Cross-Connections) using the ZQV 2.5 pluggable jumpers.

MICROSERIES Relays

Weidmuller's MicroSeries Relays are the perfect method for isolating signals or controlling digital devices. Pluggable relays are available in a variety of coil voltages. The ZQV 4N pluggable cross-connections can be used to link adjacent relay modules thereby providing a fast, secure, and professional installation. This convenient jumpering system is available on both the input and output sides of the relay which greatly reduces the wiring workload.

Maintenance is a breeze with the Weidmuller MicroSeries relay since the pluggable relay can be replaced without removing the terminal block should failure occur.

One of the first terminal block style relays to receive Class 1, Div 2 rating, the Weidmuller MicroSeries Relay can be used in hazardous areas. And -- in only 6.1mm of rail space! Dimensions of the Weidmuller MicroSeries Relay: L x W x H = 93mm x 6.1mm x 92mm