Function; Supplementary Documentation - Endress+Hauser nivotester FTC 420 Operating Instructions Manual

Nivotester FTC 420/421
Fig. 2
Summary of Nivotester FTC
420/421 front panel features
22

Function

The probe and container (or the ground-pipe of the probe) act as a
capacitor, the capacitance of which is dependent upon the level of
liquid or solids present. The electronic insert, usually mounted in
the probe head, passes a level-proportional voltage signal to the
Nivotester for evaluation. This actuates the output relay when the
preset level is exceeded or dropped below. The resulting signal
can be used to drive an annunciator, actuator or further relay.
A wire bridge on the terminal block sets the the output relay to act
in minimum or maximum fail-safe mode. The switching status of the
relay is indicated at the front panel by a red, the operational status
by a green LED. On power failure both LEDs extinguish - the
output relay de-energises.
Bridge12-13: Selection of
Max.- or Min.-Failsafe mode
Terminals 1, 2, 3:
Power supply, electrically
isolated from probe circuit

Supplementary documentation

Before proceeding with the installation of the Nivotester FTC unit,
check that the following documentation is at hand.
• Installation instructions for the capacitive probe to be used.
• Installation instructions for EC 61 Z electronic insert.
Introduction
Terminals 8, 9, 10:
Short-circuit protected
probe power circuit
Green LED:
Operational status
Red LED:
Relay status
Terminals 4, 5, 6:
Relay output