Replacement Of The Measuring Circuit Fuse; Rear Panel; Scanner Card Ho112 - Hameg HM8112-3 Benutzerhandbuch

26 A/SOURCE (4mm safety socket)
Connection of measuring cables for:
– current measurement, max. 1 ampere
– 2 wire resistance measurement
– 4 wire resistance measurement (SOURCE)
– 4 wire temperature measurement by a PT-temperature
sensor (SOURCE)
– continuity test up to 10 Ω
The maximum current may amount to 1 A
LOW (4mm safety connectors)
25
Ground connection for inputs
high-impedance DC-isolated.
27 Fuse in the current measuring circuit
The shunt is fuse-protected. The fuse (FF) is located in a fuse
holder. The measuring circuit is designed for a maximum al-
lowable measurement current of 1 ampere.
Replacement of the fuse is only allowed, after the
instrument was disconnected from the mains!
A repair of a defective fuse or bypassing the fuse is
very dangerous and absolutely prohibited!

10.9 Replacement of the measuring circuit fuse

The measuring circuit fuse 27
A replacement of the fuse is only allowed, if no voltage is applied
to the measuring connectors! Therefore all terminals V/SENSE
24 , ground 25 and A/SOURCE
cover of the fuse holder has to be turned ccw with a screw driver
having a suitable blade. As the cover can be turned it has to be
pushed by the srew driver into the fuse holder. The cover with
the fuse can then be easily taken out. Replace the defective fuse
by a new fuse of the same type having the same trip current. A
repair of a damaged fuse or the use of other means for bypassing
the fuse is very dangerous and absolutely prohibited! Damages
incurred will void the warranty.

10.10 Rear Panel

28 Power receptacle with power switch
Power receptacle for connecting the line cord with according
to DIN49457.
29 Interface
The USB/RS-232 interface is located at the rear panel of the
HM8112-3. The interface of HM8112-3 can receive data (com-
mands) from an external device (PC) or send data (measurement
values and parameters). The following option is available: HO880
IEEE-488 (GPIB). In order to avoid the warranty seal broken we
recommend the installation ex factory.
30 Voltage selector
Choice of mains voltage (115 V / 230 V).
29
!
eff
24 and 26 . Both connectors are
is accessible from the front panel.
26 should be disconnected. The
28 30
S c a n n e r C a r d H O 1 1 2
11 Scanner Card HO112 (option)
Miscellaneous:
With built-in Scanner Card HO112 voltage measurements are only
possible up to 100 V. That means that the 600 V range of the voltage
measurement functions is automatically inactive.
Pin 1 is the ground connection. Channel BP is used to supply the
other channels with current, e.g. for suppling sensors, LEDs etc.
Commands:
03A0 all channels are off
03A1 channel 1 active
03A2 channel 2 active
03A3 channel 3 active
03A4 channel 4 active
03A5 channel 5 active
03A6 channel 6 active
03A7 channel 7 active
03A8 channel 8 active
03A9 front channel
active
Pin assignment:
AHI VHI AHI VHI AHI VHI AHI VHI
19
18 17 16 15 14 13 12 11
37 36 35 34 33 32 31 30
ALO VLO ALO VLO ALO VLO ALO VLO ALO
BP CH1 CH2 CH3
Specifications
Channels: 8 (4-wire)
Switching: bistable, floating relais
Thermal voltage: typ. 500 nV, max. 1µV*)
Max. voltage between 2 contacts: 125 V
Max. measuring voltage: 125 V
Volt-Hertz-Product: ≤ 1 x 10
Max. switching current: 1 A
Max.contact resistance: approx. 1 Ω (each wire)
Life time: 2 x 10
Insulating resistance: 3 GΩ **)
Capacity: >100 pF, between contacts
Switching delay: 20 ms
Measurement delay: between 50 ms and 300 ms
*) max. 1µV after a warm-up of 1.5 h
**) at rel. humidity < 60 %
AHI VHI AHI VHI AHI VHI AHI VHI AHI
10 9 8 7 6 5 4 3
29 28 27 26 25 24 23 22 21
VLO ALO VLO ALO VLO ALO VLO ALO
CH4 CH5 CH6 CH7 CH8
pk
- also V/Ω-input -
pk
6 V · Hz
eff
8 switches (0.1 A; 10 V )
DC
Subject to change without notice
VHI
2 1
20
VLO
59