Function; Features; Product Description; Functional Description - Bender ISOMETER isoHR1685DW-925 Manual

3. Function

3.1 Features

ISOMETER® for insulated elevating work platforms
• Continuous monitoring of the insulation levels of elevating work platforms even
during operation
• Data storage to prove the insulation condition. For the burden of proof in case of an
electrical accident
• Graphical representation of the insulation resistance over time (isoGraph)
• RS-485 interface with Modbus RTU for transfer of data, alarms, acknowledgement
via existing communication to work platform
• History memory with real-time clock (buffer for three days) for storing 1023 alarm
messages with date and time
• Freely programmable digital inputs
• Automatic device self test with automatic alarm message in the event of a fault
• Connection monitoring
• Separately adjustable response values Ran1 (Alarm 1) and Ran2 (Alarm 2) for pre-
warning and alarm
• High-resolution graphic LC display for excellent readability and recording of the
device status
• Measurement of high-resistance insulation faults 100 kΩ...100 MΩ
• Automatic adjustment to high system leakage capacitances, for measuring ranges
see 11. Chapter "Technical data" on page 33

3.2 Product description

The ISOMETER® isoHR1685DW-925 is used for insulation monitoring of elevating work
platforms/overhead catenary vehicles. Working on live overhead lines in public transport
with up to 1500 V is a particularly dangerous task. To protect the workers, overhead cat-
enary vehicles are equipped with two insulation levels. Pollution, ageing or damage to
the insulation levels make the electricity perceptible to people and can lead to electrical
accidents.
The isoHR1685DW-925 makes a valuable contribution to increasing safety when working
on live parts.
The device is installed in the vehicle, continuously monitors the insulation level and in-
forms the workers immediately if the insulation level falls below certain threshold values
while driving to the work position, before and during work. Bot insulation levels can be
monitored.
9
Function

3.3 Functional description

Insulation monitoring is carried out using an active measuring pulse which is superim-
posed onto the lifting arm of the elevating work platform and the vehicle chassis via the
integrated coupling. If the insulation resistance between the lifting arm and the vehicle
chassis falls below the set prewarning response value Ran1, the "ALARM 1" LED lights up
and the relay K1 (11/12/14) switches. If the insulation resistance falls below the alarm re-
sponse value Ran2, the alarm relay K2 (21/22/24) switches and the "ALARM 2" LED lights
up.

3.3.1 Insulation monitoring

For insulation monitoring, a pulsating AC measuring voltage is superimposed onto the
elevating work platform. The measuring pulse consists of positive and negative rectan-
gular pulses of the same amplitude. The period duration depends on the system leakage
capacitances in each case and the insulation resistances of the monitored elevating work
platform.
U
m
Fig. 3.1: Pulse sequence of the measuring voltage for insulation fault monitoring
An insulation fault between the elevating work platform and earth closes the measuring
circuit. If the insulation resistance between the elevating work platform and earth falls
below the set response values R and R
an1
higher than R ), the associated alarm relays K1 (11, 12, 14) or K2 (21, 22, 24) switch. De-
an2
tected insulation faults are signalled to other bus devices via the BMS bus. In addition, the
alarm LEDs Alarm 1 or Alarm 2 light up.

3.3.2 Assignment of the alarm relays K1, K2, K3

K1 switches when the value falls below the alarm response value R
ance).
K2 switches when the value falls below the alarm response value R
ance).
K3 switches in the event of a device error or a connection fault.
t
(response value R can be set equal to or
an2 an1
(insulation resist-
an1
(insulation resist-
an2
isoHR1685DW-925_D00369_01_M_XXEN/02.2021