Equivalent & Substitute Parts for PF24-20 Semi-Toroidal Power Transformer

Part Overview

The PF24-20 is a 24VA semi-toroidal power transformer manufactured by Tamura, designed for through-hole mounting applications. It features dual primary and secondary windings with selectable voltage configurations (115V or 230V primary input; 10V parallel or 20V series secondary output). The PF24-20 is classified as obsolete, making identification of functionally equivalent substitute components essential for ongoing system support and procurement planning.

Key Parameters

Parameter	Value
Power Rating	24VA
Type	Semi-Toroidal
Primary Voltage Options	115V, 230V
Secondary Voltage (Parallel)	10V
Secondary Voltage (Series)	20V
Secondary Current (Parallel)	2.4A
Secondary Current (Series)	1.2A
Primary Windings	Dual
Secondary Windings	Dual
Mounting Type	Through Hole
Termination Style	PC Pin
Isolation Voltage	1500Vrms
Dimensions (L x W)	72.00mm x 58.00mm
Height (Seated Max)	31.80mm

Substitute Part Grouping Explanation

Substitution of the obsolete PF24-20 is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

Power rating: 24VA
Primary voltage configuration: Dual winding supporting 115V and 230V
Secondary voltage configuration: Dual winding supporting parallel 10V and series 20V
Secondary current capacity: Parallel 2.4A, Series 1.2A
Isolation voltage: 1500Vrms

Mechanical Equivalence Criteria:

Transformer type: Semi-toroidal
Mounting method: Through hole
Termination: PC pin
Physical dimensions: Compatible with 72mm length and 58mm width envelope
Height: 31.80mm seated maximum

The LP-20-1200 manufactured by Signal Transformer meets all electrical and mechanical equivalence requirements for direct substitution in applications previously using the PF24-20.

Parameter Comparison

Parameter	PF24-20 (Tamura)	LP-20-1200 (Signal Transformer)	Match Status
Power Rating	24VA	24VA	Equivalent
Type	Semi-Toroidal	Semi-Toroidal	Equivalent
Primary Voltage	115V, 230V	115V, 230V	Equivalent
Secondary Voltage (Parallel)	10V	10V	Equivalent
Secondary Voltage (Series)	20V	20V	Equivalent
Secondary Current (Parallel)	2.4A	2.4A	Equivalent
Secondary Current (Series)	1.2A	1.2A	Equivalent
Primary Windings	Dual	Dual	Equivalent
Secondary Windings	Dual	Dual	Equivalent
Center Tap	No	No	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Termination Style	PC Pin	PC Pin	Equivalent
Isolation Voltage	1500Vrms	1500Vrms	Equivalent
Dimensions (L x W)	72.00mm x 58.00mm	72.90mm x 57.20mm	Compatible
Height (Seated Max)	31.80mm	31.80mm	Equivalent
Isolation Class	1500Vrms	1500Vrms	Equivalent
Product Status	Obsolete	Active	Substitute Available

Engineering Selection Recommendations

The LP-20-1200 is the qualified substitute for the obsolete PF24-20 based on the following factors:

Electrical Compatibility: All voltage ratings, current capacities, winding configurations, and isolation specifications are identical between the two components. The LP-20-1200 delivers equivalent electrical performance in all operating modes.

Mechanical Compatibility: Both transformers share identical mounting type (through hole), termination style (PC pin), and seated height (31.80mm). Dimensional variations in length and width (72.90mm vs 72.00mm; 57.20mm vs 58.00mm) fall within acceptable tolerance ranges for through-hole mounted components and do not impact PCB layout compatibility.

Product Status and Availability: The PF24-20 is obsolete with no ongoing manufacturing. The LP-20-1200 is active production with confirmed inventory availability (1109 pieces in stock), ensuring reliable procurement for new builds and field replacements.

Regulatory Compliance: Both components share identical ECCN (EAR99) and HTSUS (8504.31.4035) classifications. The LP-20-1200 carries RoHS3 compliance and REACH unaffected status, meeting current regulatory requirements for new applications.

Frequently Asked Questions (FAQ)

Q: Can the LP-20-1200 be used as a direct replacement for the PF24-20 without circuit modifications?

A: Yes. The LP-20-1200 is electrically and mechanically equivalent to the PF24-20 across all specified parameters. No circuit modifications are required for substitution in applications previously using the PF24-20.

Q: Are there dimensional differences between the PF24-20 and LP-20-1200?

A: Minor dimensional variations exist: the LP-20-1200 measures 72.90mm length (vs 72.00mm) and 57.20mm width (vs 58.00mm). These differences are within acceptable tolerance for through-hole mounted transformers and do not affect PCB mounting compatibility or performance.

Q: What is the isolation voltage rating for both transformers?

A: Both the PF24-20 and LP-20-1200 are rated for 1500Vrms isolation voltage, providing equivalent electrical isolation performance.

Q: Why is the PF24-20 listed as obsolete?

A: The PF24-20 is no longer in active production by Tamura. The LP-20-1200 from Signal Transformer provides equivalent functionality and is currently in active production with available inventory.

Q: Are the winding configurations identical between the two transformers?

A: Yes. Both transformers feature dual primary windings and dual secondary windings with no center tap. Both support identical voltage configurations: 115V or 230V primary input, and 10V parallel or 20V series secondary output.

Q: What is the maximum output current for each voltage configuration?

A: In parallel configuration (10V secondary), maximum output current is 2.4A. In series configuration (20V secondary), maximum output current is 1.2A. Both transformers deliver identical current ratings.

Q: Are there any compliance or certification differences between the two parts?

A: The LP-20-1200 carries RoHS3 compliance and REACH unaffected status. Both components share identical ECCN and HTSUS classifications. The LP-20-1200 meets current regulatory requirements for new applications.

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