HP Hewlett Packard 9100-4117 5KVA Doubly Shielded Isolation Transformer 120V

HP Hewlett Packard 9100-4117 5KVA Doubly Shielded Isolation Transformer 120V

The Hewlett Packard 9100-4117 is a 5 KVA doubly shielded isolation transformer designed for use in laboratory, test, and precision electronic environments. It features both a primary shield braid and a secondary shield braid, providing two stages of electrostatic shielding between the primary and secondary windings to suppress common-mode noise and ground loops. The primary windings accept selectable input taps at 100V, 110V, or 120V, making the unit usable across a range of AC mains standards. The secondary is jumper-configurable for either 120V or 240V output.

Specifications & What's Included

• Manufacturer: Hewlett-Packard
• Model / Part Number: 9100-4117
• Total Power Rating: 5.0 KVA (5000 VA)
• Primary: Dual windings, each with taps at 0V / 100V / 110V / 120V
• Primary Frequency: 44–66 Hz
• Secondary: Dual windings, each 120V
• Secondary Output — 120V configuration: 41.67A (jumpers 9-11 / 10-12)
• Secondary Output — 240V configuration: 20.83A (jumpers 10-11 / 9-12)
• Shielding: Doubly shielded — Primary Shield Braid and Secondary Shield Braid
• Phase: Single phase
• Mounting: Open-frame transformer core mounted on a wheeled black steel dolly/cart
• Output leads present (orange and black)
• Terminal cover box with high-voltage warning label

Applications

Doubly shielded isolation transformers like the HP 9100-4117 are standard power conditioning equipment in electronic test laboratories and precision instrument setups. The double-shield construction — a grounded electrostatic shield on both the primary and secondary sides — provides exceptional attenuation of capacitively coupled noise between the AC mains and the load, making these transformers well suited for powering sensitive test instruments, oscilloscopes, signal analyzers, and data acquisition systems where ground-loop interference and common-mode noise must be minimized. Hewlett-Packard specified and supplied these transformers as system-level accessories for their own instrument racks and test station configurations during the 1970s and 1980s, ensuring a clean, isolated AC supply for HP measurement equipment. They continue to be valued today in lab environments, audio electronics, and any application requiring high-quality AC isolation with low leakage current. The jumper-selectable secondary (120V or 240V) adds flexibility for different load requirements without rewiring.