UNI-T UT8805E Manual page 4

Limit Protection of Input Terminal:
1) Main input terminal HI and LO
The input terminals HI and LO apply to voltage, resistance, capacitance, continuity, frequency and diode
measurements.
a. HI-LO limit protection: the HI-LO limit is maximum 1000V DC or 750V AC voltage, which can also be
expressed as maximum 1000Vpk.
b. LO-GND limit protection: the limit of input terminal LO-GND can safely float to 500Vpk. The limit of
the terminal HI-GND is maximum 1000Vpk. Therefore, the sum of floating voltage and measured
voltage shall less than 1000Vpk.
2) Sampling terminals Sense HI and LO sense
Terminal Sense HI and LO sense are used for 4-wire resistance measurement.
a. The limit protection of Sense HI-LO sense is 200Vpk.
b. The limit protection of LO sense-LO is 2Vpk.
3) Current input terminals mA and A
a. The terminal mA and terminal LO are used for current measurement below 200mA. The fuse on rear
panel provides a maximum current limit protection 250mA for mA terminal.
b. The terminal A and terminal LO are used for current measurement from 200mA to 10A. The fuse on
rear panel provides a maximum current limit protection 10A for terminal A.
Note: the voltage of the current input terminal is similar to that of terminal LO. To maintain good
protection, only the specified type and class fuses can be replaced.
IEC Measurement Category II Overvoltage
To avoid shock hazards, UT8805E provides overvoltage protection for mains connections that meet both
conditions below.
1. The input terminals HI and LO are connected to the mains under the measurement class II condition
(described below).
2. The maximum voltage of the mains is 300V AC.
WARNING: IEC measurement category II includes electrical devices connected to mains by a socket on
a branch circuit, such as most small appliances and measuring instruments. UT8805E can apply to make
following measurements: input terminals HI and LO are connected to the mains of IEC measurement
category II devices (maximum 300V AC) or are connected to branch outlets. However, the input terminals
HI and LO cannot be connected to the mains of permanently installed electrical device, such as the
distributor of main circuit breaker, the cut-out box of sub-distributor, or the permanently connected motor,
because these devices and circuits are prone to be overvoltage.
CAUTION: voltages above 300V AC can only be measured in circuits that disconnected from the mains.
However, transient overvoltage also exists in this kind of circuits. UT8805E can safely withstand
accidental transient overvoltage up to 2500Vpk. Do not use the device to measure circuits if the transient
overvoltage may exceed this range.
UT8805E Benchtop Digital Multimeter
Protection
4