Philips PM2528 Operating Manual page 44

44
6.2.2.
6.3.
— decimai-point representation e
— unit representation Display {units} Function
a V~,V ~, Vpeak, VhF
Qaw, Q4aw
Ax, Ay
highest value
lowest value
peak-to-peak value
o<
~~ overload indication OL
—~ crest factor indication Lin the teast significant digit shows that the input circuit is overloaded ie
{in functions V~, V ~,V peak due to an input signal with an excessive crest factor.
and A>)
Rear panel
Analog output {optional) :
A galvanically-separated analog output signal, which is proportional to the input signal, is available when the
analog output option PM9254 is used.
Digital interface (optional)
— PM9291: IEC625 interface
The PM2528 can be remotely controlled on all functions, ranges and modes and the measuring result can be read
out via the bus,
— PM9292: parallel output.
The measuring result and the function code are available in BCD parallel format, Also a start command can
be given,
Ext. start (BNC)
A measuring cycle can be started by supplying a logic "0" level to this input or by short-circuiting when the
EXT START mode is selected,
Mains socket
The PM2528 is provided with a combined mains socket and fuse holder, in which also a spare fuse is situated.
Earth terminal
Protective earth terminal, Refer to section 5.1.2. on page 41,
GUARD
The digital multimeter PM2528 is equipped with a GUARD. This GUARD is a shield between LO and earth
which increases the leakage impedance.
Increasing the leakage impedance improves the common mode rejection.
The GUARD may be connected to the circuit via a separate lead.
Proper use of the GUARD provides a better common mode rejection and a higher measuring accuracy,
especially in the most sensitive ranges.
For an optimum GUARD connection, the following rules should be taken into account:
— Connect the voltage to be measured to the PM2528 by means of a shielded measuring cable. This cable
should not run parallel to heavy current cables.
— Connect the GUARD to the same potential as the 0 input terminal.
— Connect the GUARD in such a way that no common mode current fiows through any source impedance.