TM 11-6625-444-14-1
OPERATING
INSTRUCTIONS
Section 1. CONTROLS AND INSTRUMENTS
sequently capable of a fully floating measurement
3-1. General
without degradation of accuracy.
This section describes overload protection and
b. Guarded measurements will be necessary
guarded measurement features of the voltmeter.
under the following conditions:
It also contains an illustration which locates and
(1) Long signal leads together with a high
describes each control, connector and indicator.
source impedance.
3-2. Damage From Improper Settings
(2) During floating measurements when
The voltmeter is fully protected from overloads
common mode voltage is at a high potential, high
applied to the input terminals in all ranges and
frequency, or both conditions exist.
modes of operation. In the VDC and RATIO
(3) During operation of the voltmeter in the
functions, 1100V DC or RMS (1500V peak to
presence of high level, radiated noise, an example
peak) can be applied to the input without dam-
of which is stray fields at the powerline frequency.
aging the volt meter. Potentials of up 150 vdc
c. Under normal op crating conditions (absence
can also be applied to the external reference input
of common mode signals), the GUARD terminal
terminals without damaging the voltmeter.
in the input terminal group shall be connected to
the LO terminal. A slide strap is provided at the
GUARD terminal for convenience in connection.
a. A system of internal shields and guards
NOTE
Breve been included in the design and construction
INPUT terminals on the front panel and
of the voltmeter. These shields and guards can be
rear panel are connected in parallel.
connected as shown in figure 3-1 to minimize
Always check both terminal groups to
common mode-to-normal mode signal conversion
insure desired connections are made.
and induction o f n o i s e . T h e resulting
measurement process in the voltmeter is sub-
