Product Overview
Product OverviewIndustrial Relays
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This portion of the selection guide covers industrial relays. Industrial relays are used for:
- Safety applications
- Applications requiring long life
- Hazadous Areas and Difficult Environments
- Latch and Pneumatic Timers
Safety Features
Industrial relays have important features that provide safe, more reliable design of control systems.
- Mechanically linked contacts (positive-guided contacts)
- Double-break contacts make it possible to detect a welded contact and also reduce the posibility of welding a contact.
- Break before make contacts (non-overlapping)
Importance of Mechanically Linked Contacts
This feature allows detection of a welded contact condition. In most relays, each contact opens and closes independently of the other contacts. Mechanically linked (also known as positively guided and Direct Drive™) contacts are linked together, thereby preventing the reclosing of the N.C. contacts if a N.O. contact has welded.
Importance of Double-Break Contacts
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This design provides better protection against contact welding than single break design. Other benefits include greater DC load breaking capability and better isolation. It also provides separation of N.O. and N.C. circuits, unlike standard "Form C" contacts. Double-break contacts open the circuit in two places, creating two air gaps. It is analogous to having two contacts in series.
Long Life
Allen-Bradley industrial relays and contacts are designed for long life. Each component is engineered for millions of operations, without compromising peformance. Contact life is often 3 to 5 times greater than plug-in relays.
Safety Applications:
Allen-Bradley industrial relays are frequently used in safety circuits for:
- Safety relay output to expand the current rating or contact life of a safety relay
- Master Control Relays (switching PLC power supplies)
- E-Stop Relays
- Directing course of action when a safety condition occurs
- Light curtain monitoring
- Press control
Additional Features and Options
- Switch up to 12 circuits with one relay
- Sealed contacts for dirty enviroments and low-energy switching
- Coil voltages from 12…600V AC and 6…600V DC
- Switch from 5…600V AC and DC
- Switch from 1 mA…35 A
- Pneumatic timers to maintain timing even if power is lost
Relay Load Life Comparison—Pilot Duty Loads (solenoid valve, contactor coil, relay coil)
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Safety Relay Output Block Diagram
This diagram illustrates how 2 industrial relays can be used to expand safety relay outputs.
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Note: 1 CR and 2 CR are Allen-Bradley Industrial relays with mechanically linked contacts (Bulletins 700-P, 700-CF, and 700-M)
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| Bulletin. No. | 700-M/MB | 700-CF | 700S-CF | 700-P | 700S-P | 700-R |
| Mechanically Linked contacts¬ | YT | Y | Y | Y‡ | Y‡ | N |
| Double-break contacts | Y | Y | Y | Y | Y | — |
| Switch millions of operations at >1 A | Y | Y | Y | Y | Y | Y |
| Low-energy switching | Y | Y | Y | Y | Y | Y |
| Marine certification—vibration applications | Y | Y | Y | Y | Y | Y |
| Relay Differences | ||||||
| Number of circuits to switch (number of poles) | 4…8 | 4…10 (AC) 4…8 (DC) |
8 | 2…12 | 2…12 | 2…8 |
| Current ratings at 120V AC | 10 A | 10 A | 10 A | 10…35 A | 10 A | 5 A |
| Pneumatic timer option | N | Y | N | Y | N | Y |
| Electronic timer option | Y | Y | Y | Y | N | Y |
| Latch option | N | Y | N | Y | N | Y |
| Built-in surge suppression for 24V DC coil option | Y | Y | Y | N | N | Y§ |
| Convertible and replaceable contacts | N | N | N | Y | N | Y |
| Switch 20…35 A on 6…12 poles | N | N | N | Y | N | N |
| DIN Rail Mounting | Y | Y | Y | N | N | N |
| Finger-Safe Terminals | Y | Y | Y | N | N | N |
| Poles permanently attached | N | N | Y | Y | Y | Y |
| ¬ If a N.O. contact welds, the N.C. contacts will remain open and if a N.C. contact welds, the N.O. contacts will remain open. | ||||||
| T Yes for main poles only. | ||||||
| ‡ Bulletins 700-P and 700S-P meet the component requirements for relays of ANSI B11.19 section 5.5.1 (Control Reliability). | ||||||
| § Y for AC coil. | ||||||