The MTL TP-Pipe series surge protector safeguards field-mounted process transmitters where it matters, right at the unit. The TP-Pipe
screws directly into the conduit entry, with no additional modification. After this simple installation, it provides high-level protection
against surges and transients while normal operation remains unaffected.
The TP-Pipe protection network consists of high-power, solid-state electronics and a gas-filled discharge tube capable of diverting 20kA
impulses. The whole unit is encased in an ANSI 316 stainless steel housing, threaded for the common conduit entries used on process transmitters.
Versions are available for 1/2" NPT, 20mm ISO, and G 1/2" (BSP 1/2 inch) threaded entries.
Installation of the MTL TP-Pipe is very simple and can easily be carried out retrospectively to existing installations. The TP-Pipe screws directly
into the conduit entry on the transmitter case and flying leads are connected to the terminal block and the internal earth stud. Field wiring is
connected to a three position socket and then connected to the provided header. They operate without in any way affecting normal operation, passing
ac or dc signals without attenuation while diverting surge currents safely to earth and clamping output voltages to specific levels.
The all-important earthing connection is made to the local casing of the transmitter with no separate earth connection or ground stake at the transmitter
being needed. In operation, the TP-Pipe makes sure that the transmitter electronics are never exposed to damaging transients between lines or between
lines and casing/earth. Any surge current appearing as a series-mode or common-mode transient is converted into a common-mode voltage - whereupon the
transmitter electronics are temporarily raised to some higher voltage level before ‘floating' down automatically (and without damage) to resume normal
operation.
For hazardous-area use, approvals for both intrinsically safe and flameproof (explosion-proof) operation are available in all gas groups and apparatus
temperature classification up to T4. Where transmitters are used in circuits suitable for Div 2/Zone 2 installations, the TP-P can be added without
adversely affecting the level of safety.
For Fieldbus applications, use the TP-P-32 which meets the requirements of IEC61158-2:2004 and ANSI/ISA-50.02-2 1992 for 31.25kbit/s systems as used by
Foundation™ fieldbus, PROFIBUS-PA and WorldFIP.
