On a packaging-line retrofit RFQ, the relay module line item must read as a complete I/O substitution, not as a generic "relay" purchase, because most requote cycles on packaging machines trace back to three omissions: coil voltage mismatch, undersized contact rating on inductive valve loads, and a socket or footprint the existing cabinet cannot accept [S1].
A relay module on a conveyor sorting line retrofit typically drives 24 V DC solenoid valves, 110/230 V AC indicator lamps, and 24 V DC photo-eye commons, so the RFQ must force the supplier to quote a single relay family that covers all three load classes, with rated current, contact form, and socket type written against each station [S1].
Coil voltage, dropout, and ride-through
Coil voltage must be stated on the RFQ as a single value, typically 24 V DC for PLC-driven cabinets or 110/230 V AC for legacy panels, because specifying a range such as "24 V DC" without naming the tolerance window lets a supplier ship a relay with an 18-30 V wide-range coil that may not drop out cleanly when the upstream 24 V rail sags to 21 V under inrush [S1].
For a vacuum packaging machine retrofit where the seal heater transformer draws 8-12 A in the first 200 ms, write the RFQ with an explicit minimum dropout voltage (commonly 10% of nominal, i.e. 21.6 V on a 24 V DC coil) and a surge-withstand note, so the chosen relay does not chatter during the seal cycle [S1].
Coil surge suppression is a required line: ask for a built-in flyback diode on 24 V DC coils and a built-in RC snubber or varistor on 110/230 V AC coils, and require the supplier to state the surge energy in joules, because retrofits into cabinets without external suppressors will fail within 2-3 years if the relay itself does not absorb the inductive kick [S1].
Contact arrangement, rated current, and load class
The contact arrangement field must be written station-by-station, not as a single "SPDT" string, because a molding line typically mixes 1 NO for a clamp, 1 NC for a safety gate, and 1 SPDT for a position sensor, and forcing the supplier to quote one form per station prevents them from substituting a 1 NO relay into an NC interlock seat [S2].
Contact rated current is the single most common source of requote cycles: for resistive loads the figure is straightforward (commonly 10 A at 250 V AC, 10 A at 30 V DC), but on the RFQ you must also call out the inductive load rating, because most packaging-line relays drop to 1/3 of the resistive rating on a solenoid or motor contactor coil, and a supplier quoting only the 10 A resistive figure will ship a relay that welds its NO contact within weeks [S1].
For 24 V DC inductive loads on a packaging machine, insist on a minimum DC-13 / inductive load rating of 2-3 A and a TV-8 or equivalent tungsten rating for any lamp load above 60 W, because a relay rated only "10 A / 250 V AC resistive" has no published DC inductive life and will fail qualification at the first valve [S2].
Socket, footprint, and wiring method
Socket type belongs on the RFQ as a closed list, not as an open "DIN rail mount" note, because most retrofit cabinets were wired to a specific socket family (the typical pattern is a 14-pin octal, an 11-pin round, or a 4-pole blade socket) and the relay module is only as retrofittable as the socket under it [S3].
If the retrofit must reuse existing panel cutouts and wiring harnesses on an automatic molding line, state the legacy socket part number, the pin pitch, and whether the wiring is screw, spring-clamp, or push-in, because a screw-to-spring migration forces re-stripping every conductor and a full I/O re-termination, which is the difference between a one-shift swap and a three-day panel rebuild [S3].
For greenfield sub-panels inside a retrofit, name the next-generation socket pattern (blade-type, 5.0 mm pitch) and the matching cross-reference, then add a "must accept identical wiring layout" line so the installer does not have to redraw the schematic, and so the supplier cannot bid a relay that fits the socket but routes the common terminal to a different pin [S1].
Electrical and mechanical endurance
Endurance figures must be on the RFQ as two separate numbers, not as a single "long life" string: a typical industrial relay on a packaging line is specified at 10 million mechanical operations and 100 thousand electrical operations at full rated load, and the electrical number is the one that actually determines service life because contact wear dominates in a continuous-running cabinet [S3].
Cycle the supplier on a duty-cycle assumption that matches the line, because a conveyor sorting line running 30 cycles per minute through a diverter will log 14.4 million electrical operations per year against the 100 thousand rating, while a slower vacuum packaging machine at 6 cycles per minute logs under 3 million, and the same relay part number is not a 5-year part on both [S1].
Ask for a verified electrical life at the actual load, not at the maximum resistive rating, because the same relay published at 100 thousand operations at 10 A resistive will typically drop to 30-50 thousand operations at 3 A inductive on 24 V DC, and only a published DC-13 / AC-15 curve at your load class lets you predict the replacement interval [S3].
Approvals, environment, and failure mode
Approval marks are a hard-gate line on the RFQ: list the regional marks the cabinet must carry, commonly CE for the European market and UL or cUL for North American builds, and require the supplier to state the certificate number on the quote, because a CE-marked relay built to a non-harmonised standard will fail the panel's Declaration of Conformity even if it works electrically [S1].
For washdown zones on a packaging machine, write an IP rating into the relay-module line when the socket is open, typically IP20 for finger-safe on the operator side and IP54 to IP65 only when the relay is potted or sealed, because an unsealed relay and socket pair in a wet zone will fail the insulation test within 12 months [S2].
Failure mode is the line most buyers forget: ask for a "fail-safe on loss of coil" statement, especially for safety-gate and over-temperature interlocks on a molding line, and require an NC contact on those circuits, because a NO-only relay in a safety seat will leave the guard open when the coil loses power, which is the opposite of what the safety circuit assumes [S1].
RFQ line structure that closes the requote loop
The relay-module line should be written as one row per station with these columns filled: station tag, coil voltage with tolerance, contact form, contact rated current at AC-1 / DC-13, socket type and pin reference, suppression built-in yes/no, approval marks, and quantity, and the supplier must not be allowed to reply with a single line item, because a single-line reply hides the substitutions that turn into field failures six months after commissioning [S1].
Cross-reference back to the counter spec line for OEM control cabinets so the relay logic and the counter logic share the same supply rail and the same socket family, and pair the relay module with a belt tensioner spec for any mechanical sub-assembly on the same retrofit, because the two items usually share a shutdown contact and a common 24 V DC return [S1].
Two trackable signals for the next purchase: a published DC-13 / AC-15 endurance curve at the actual station load, and a relay-socket cross-reference table matching the existing cabinet cutout, both delivered as PDF attachments with the quote, not as verbal claims, because verbal claims about relay life are the single most common source of an acceptance-test failure on a packaging-line retrofit [S3].