Littelfuse V18ZS2 Equivalent & Substitute Parts

Part Overview

The Littelfuse V18ZS2 is an 18 V, 500 A varistor in a through-hole disc 10mm package, designed for transient voltage suppression applications. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. Active alternatives from Littelfuse maintain identical electrical and mechanical specifications while offering current product status and improved supply chain availability.

Key Parameters

Parameter	Value
Varistor Voltage (Typical)	18 V
Current - Surge	500 A
Maximum AC Volts	10 V
Maximum DC Volts	14 V
Energy	1.5 J
Capacitance @ 1 MHz	5300 pF
Operating Temperature Range	-55°C to 85°C
Mounting Type	Through Hole
Package / Case	Disc 10mm
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the V18ZS2 is determined by strict equivalence across all electrical and mechanical parameters. The following criteria define valid substitutes:

Varistor voltage range: 16.2 V (minimum) to 19.8 V (maximum)
Surge current rating: 500 A
Energy dissipation: 1.5 J
Capacitance: 5300 pF @ 1 MHz
Operating temperature: -55°C to 85°C
Mounting configuration: Through hole, disc 10mm package
Regulatory compliance: ROHS3 compliant

All substitute parts listed maintain these parameters without deviation. Differences exist only in product status (active vs. obsolete), packaging format (bulk vs. tape & reel), and series designation (ZS, ZT, ZU).

Parameter Comparison

Part Number	Manufacturer	Series	Product Status	Packaging	Varistor Voltage (Typ)	Surge Current	Energy	Operating Temp	RoHS Status
V18ZS2	Littelfuse Inc.	ZS	Obsolete	Bulk	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZS2P	Littelfuse Inc.	ZS	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZS2PX2855	Littelfuse	ZS	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZT2P	Littelfuse	ZT	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZT2PX2855	Littelfuse Inc.	ZT	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZU2P	Littelfuse Inc.	ZU	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant
V18ZU2PX2855	Littelfuse Inc.	ZU	Active	Tape & Reel	18 V	500 A	1.5 J	-55°C ~ 85°C	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts are electrically and mechanically equivalent to the V18ZS2. Selection among substitutes should be based on the following factors:

Product Status: The V18ZS2 is obsolete. All substitute parts listed carry active product status, ensuring continued manufacturer support and supply chain stability.

Packaging Format: The V18ZS2 is supplied in bulk packaging. Substitutes V18ZS2P, V18ZT2P, V18ZU2P, and their X2855 variants are supplied in tape & reel format, suitable for automated assembly processes. Tape & reel packaging is standard for active production parts.

Regulatory Compliance: All parts maintain ROHS3 compliance. Substitute parts with REACH Unaffected designation provide additional regulatory documentation for applications requiring extended compliance tracking.

Series Designation: The ZS, ZT, and ZU series designations indicate internal manufacturing variations within Littelfuse's varistor product line. All three series maintain identical electrical performance for the 18 V, 500 A specification.

Availability: Substitute parts demonstrate consistent inventory levels across all variants, supporting both immediate procurement and long-term supply planning.

Frequently Asked Questions (FAQ)

Q: Can V18ZS2P be used as a direct replacement for V18ZS2?

A: Yes. V18ZS2P is electrically and mechanically identical to V18ZS2. The primary difference is product status (active vs. obsolete) and packaging format (tape & reel vs. bulk). Both maintain the same 18 V varistor voltage, 500 A surge current, and through-hole disc 10mm configuration.

Q: What is the difference between V18ZS2PX2855 and V18ZS2P?

A: Both parts are electrically equivalent with identical electrical specifications. The X2855 designation indicates a specific manufacturing or packaging variant. Selection between these parts should be based on supplier availability and internal procurement requirements.

Q: Are ZS, ZT, and ZU series parts interchangeable?

A: Yes, for the 18 V, 500 A specification. All three series maintain identical electrical and mechanical parameters. Series designation reflects internal Littelfuse manufacturing classifications and does not affect circuit performance or compatibility.

Q: Does tape & reel packaging affect electrical performance?

A: No. Tape & reel packaging is a delivery format only and does not alter the electrical characteristics or performance of the varistor. It is optimized for automated assembly processes.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance. Substitute parts with REACH Unaffected status provide additional regulatory documentation for applications requiring extended compliance verification.

Q: What is the operating temperature range for all substitute parts?

A: All substitute parts operate across the same temperature range: -55°C to 85°C. This specification is maintained across all series and packaging variants.

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