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Open-frame transformer with foot mounting and wire leads

Robertshaw

Robertshaw 620-501 Class 2 Transformer 50 VA 28V AC 120/208/240V AC

SKU CH-AWR7-RD94Z

Class 2 transformer delivering 28 V AC at 50 VA from 120, 208 or 240 V AC inputs with primary fuse protection and NEMA 1 open enclosure

  • TypePower Quality & Distribution
  • Delivers stable 28 V AC output for reliable control circuits
  • 50 VA rating handles moderate loads without overheating
  • Accepts 120, 208 or 240 V AC input for flexible installation
  • Primary fuse protects the transformer from over-current damage
  • NEMA 1 open enclosure suits indoor mounting with foot or hub plate

Robertshaw 620-501 Class 2 Transformer

The Robertshaw 620-501 is a Class 2 transformer rated at 50 VA with a 28V AC output. It accepts 120V, 208V, or 240V AC input at 50 Hz or 60 Hz single phase. The unit features an open NEMA 1 enclosure with foot mounting on a universal 1/2 in hub plate.

Suits low-voltage control circuits needing 28V AC

This transformer suits HVAC controls, thermostats, and similar Class 2 circuits that require a 28V AC supply from standard mains voltages. It is not for applications that demand a higher VA rating, a different output voltage, or an enclosed NEMA rating beyond NEMA 1.

Verify your mains voltage

Confirm your supply matches one of the three input voltages and that 50 VA covers the connected load. Ensure the foot-mount hub plate fits your enclosure and that screw terminals suit your secondary wiring. The primary side uses 8 in leads for connection.

Highlights

  • Delivers stable 28 V AC output for reliable control circuits
  • 50 VA rating handles moderate loads without overheating
  • Accepts 120, 208 or 240 V AC input for flexible installation
  • Primary fuse protects the transformer from over-current damage
  • NEMA 1 open enclosure suits indoor mounting with foot or hub plate

Specifications

BrandROBERTSHAW
TypePower Quality & Distribution

Questions about this item

What voltage supply must the site already provide for the 120/208/240 V AC primary?

The transformer accepts 120 V, 208 V or 240 V AC at 50 or 60 Hz, so the building must supply one of those three voltages.

Can the 28 V AC secondary feed legacy 24 V thermostats or relays?

The secondary is rated 28 V AC at 50 VA; verify that existing 24 V devices tolerate the higher open-circuit voltage before connecting them.

How do I confirm the unit is operating correctly after wiring the 8 in primary leads and screw terminals?

Measure 28 V AC across the secondary screw terminals with a multimeter while the primary is energised; the primary fuse should remain intact.

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