Insulation Resistance Measurement - Saluki STB6684 Operation Manual

STB6684/A Operation Manual
stations, the fine charge stations must have individual return paths and they must have a return path
to the HV1 (H.V.). Furthermore, the wiring of the I in connection must be parallel to the wiring of
the HV1. This ensures both minimum hum susceptibility and maximum protection against
flash-overs. In order to shield the I in connection from capacitively coupled noise the Guard
connection should be used all the way to the IR test station. The end of the shield must never be
connected to anything but the shield of the I in connector.
Even though there is a demand of easy replacement of charge resistors, it is recommendable to
place protection resistors near the charge stations. These reistors should be wirewound types of
2-3W and values of 10-100Ω.
In sorting machines the chassis is well grounded and the individual parts are well interconnected.
This means that the wiring to the test equipement has considerable stray capacitance to earth
ground. It is therefore recommendable to have individual mains filters on all test equipment within
the sorting machine. The mains filters must be well connected to the chassis near the test equipment.
This also minimizes influence between measuring equipment, computers motor controls, etc.

6.6 Insulation resistance measurement

Scope
When measuring Insulation Resistance (IR) with STB6684/STB6684A, there are several issues
to consider when comparing to resistance measurement with a common multimeter. This
application note is intended to address some of these.
General
In its simplest form an IR test is performed by applying a DC voltage over the isolation barrier and
measure the corresponding DC current, often referred to as "leakage current" (which should not be
confused with the leakage current measured applying an AC test voltage). The IR is then calculated
from: IR = UHT / I
Leak
HT
GND
Current
Meas.
GND
Figure 6.6.1 Standard IR Measurement
Figure 6.6.1 shows the basic setup for IR testing.
(1)
C
I
◇ 81
Chapter 6 Measurement Procedures and Examples