Contactless Power Transfer With the Securitron® PowerJump™

Transfer power wirelessly across a door gap to power electrified hardware


Let’s face it, running wire from the jamb to the door lock mechanism is not always fun. Over the years, the task has become easier with the development of power transfer devices using controllable Bellhanger’s Bits, fiberglass rods and door coring tools.

Before the introduction of the Securitron® PowerJump™, no manufacturer had developed a saleable product that can transfer 12 or 24VDC power from the swing or hinge side, the top or bottom of a door to the lock mechanism without physical contact.

The Securitron PowerJump, patent number 8,294,302, relies on inductive coupling power transfer (ICPT). This “contact-free and wireless” transfer mechanism provides up to 500mA@12VDC or 250mA @24VDC at the door. The voltage is set at the door unit.

To describe the operation of inductive coupling power transfer, Securitron uses the example of the electric toothbrush, which sits on the power supply to be charged. There is no direct electrical contact. The power moves from the charger through two plastic housings into the toothbrush battery. A post on the battery charger slides into the opening in the brush assembly to ensure proper alignment.

Inductive coupling is the result of magnetic fields generated during the flow of electricity within a wire coil. When fluctuating power is applied to a coil, a changing magnetic field is created. The power within this magnetic field can be induced to transfer to another exact frequency coil in range, providing contactless low voltage transfer of power. The range of the induced field is limited by the wavelength. For the Securitron PowerJump, the range is approximately 3/16” between the frameside unit face and the doorside unit face.

Because this dimension is larger than the gap between a door and the jamb, the frame unit can be installed into the hinge or lock side of the jamb or into the header. The door unit is then installed into the door.

To gain the maximum amount of amperage, alignment of the door and frame units is critical. They must be horizontally and vertically aligned. If there is significant misalignment, the power will not transfer. They must be directionally within less than 3/16” of each other to transfer power.

The PowerJump can be used to power electrified door lock hardware that requires up to six watts (0.5A@12VDC). The PowerJump was designed for Fail Secure devices.

Installation

For the purpose of this article, we installed the Securitron PowerJump into the right leaf of a double medium stile aluminum glass door entry. Both of the doors are equipped with mid rails, each having two glass panes. Both of the outswing doors were mounted using aluminum continuous hinges. Each is equipped with a Sargent 8800 rim exit device. A removable mullion provides the latching for the exit devices.

Note: Power was shut off to this opening.

The right door is equipped with the Sargent 774ETL exterior trim with the “L” lever. This solenoid controlled trim provides remote locking and unlocking of the exterior lever. This Fail Secure trim was ordered with a 24VDC solenoid operating at 250mA. The left door is equipped with the Sargent 704 ETL key override rim cylinder in the exterior trim.

The original installation specified a surface door cord to transfer power from the jamb to the door. The installation of the PowerJump was necessary because the door cord was being vandalized, disabling card access and requiring a key to gain entry. Installation of the Securitron PowerJump did away with the exposed wiring, eliminating the problem.

To keep things simple, we decided to locate the PowerJump on the hinge side of the door at about the same height as the door loop. This proved advantageous since the thickness of the continuous hinge leaf is approximately the same as the thickness of the PowerJump face. No mounting tabs were necessary because the PowerJump could be mounted directly onto jamb.

The template was positioned onto the jamb side of the continuous, offset to be as close to the middle of the door edge. The continuous hinge is wider than the door as the gear cap and a portion of the leafs are exposed.

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