The Tap-4-PLUS is the newest instrument by Zensol for OLTC testing. It has 2 more analog inputs than the TAP-4. The TAP-4-PLUS with the TAP-DRM accessory can perform dynamic resistance and vibration recordings at the same time. Doing so will allow you to easily understand the vibration impacts.
Like the TAP-4, the TAP-4-PLUS can test all types of OLTC: resistor, reactor, or vacuum, of any brands (Maschinenfabrik Reinhausen (MR), ABB, Federal Pioneer, Ferranti, etc.).