Danfoss VLT FC Installation guide

MAKING MODERN LIVING POSSIBLE

Instruction

VLT® FC Series Drives Leakage Current Monitor Module

RCMB20/RCMB35

1.1

VLT® Leakage Current Monitor Module

VLT® Leakage Current Monitor Module

1 1

1.1.1 Intended Use

The AC/DC sensitive leakage current monitoring modules
RCMB20-500-01 and RCMB35-500-01 are used for fault
current monitoring in applications, where frequency
converters are used, and direct and/or alternating fault
currents are likely to occur.
Each module has to be installed and connected in the
cable connection compartment in front of the mains input
of the frequency converter.
Both variants of the modules provide an output signal

4...20 mA proportional to the high frequency leakage
current.

Warning

1.1.2

Only intended for use to protect equipment and not for
personal protection.

Table 1.1 Approval

Device Features

1.1.3

1.1.4

Functional Description

After switching the supply voltage on, the multi-colour LED
shows a green light and the leakage current monitoring
module carries out a self test.
The leakage current monitoring module measures both AC
and DC currents. The r.m.s. value is calculated by summing
up the DC components included in the leakage current
and the AC components that are below 500 Hz. A current
signal of 4…20 mA proportional to the rms value is
provided at the module output. The analogue value is
updated at the latest every 20 ms.

Every two seconds, the leakage current monitoring module
cyclically tests the connection to the measuring current
transformer and the correct functioning of the AC and DC
measurement. In addition, the supply voltage is monitored
continuously. If a fault occurs, the multi-colour LED flashes
red and the analogue DC output current is 20 mA.

LED Indication of Operation Status

1.1.5

LED continuously lights green = normal operating
condition
LED flashes red = fault
Examples of possible faults:
connection fault, current transformer fault, module fault
etc.

AC/DC sensitive measured value acquisition

•

Frequency range 0…500 Hz

•

Measuring current transformer, inside diameter 20

•

mm/35 mm
Measuring range 500 mA

•

Measuring time ≤ 180 ms

•

Supply voltage 24 V DC

•

Analogue output current 4…20 mA

•

CT connection monitoring using cyclical test

•

current
LEDs: power On LED, alarm LED

•

MI38U302 - VLT® is a registered Danfoss trademark 1