Ground Leakage Current; Extreme Running Conditions - Danfoss VLT Compressor Drive CDS 803 Design Manual

Product Overview
SMPS
1
2
3
a
1 Power supply (SMPS)
2 Optocouplers, communication between AOC and BOC
3 Custom relays
a Control card terminals
Illustration 2.9 Galvanic Isolation
CAUTION
Installation at high altitude:
At altitudes above 2000 m (6562 ft), contact Danfoss
regarding PELV.

2.10 Ground Leakage Current

WARNING
DISCHARGE TIME
Touching the electrical parts could be fatal - even after
the equipment has been disconnected from mains.
Also make sure that other voltage inputs have been
disconnected, such as load sharing (linkage of DC
intermediate circuit), and the compressor connection for
kinetic back-up.
Before touching any electrical parts, wait at least the
amount of time indicated in Table 2.1.
Shorter time is allowed only if indicated on the
nameplate for the specific unit.
MG18N202
Design Guide
NOTICE
Leakage current
The ground leakage current from the frequency
M
converter exceeds 3.5 mA. To ensure that the ground
cable has a good mechanical connection to the ground
connection, the cable cross-section must be at least 10
2
mm (8 AWG) Cu or 16 mm
ground wires terminated separately.
Residual current device protection RCD
This product can cause a DC current in the protective
conductor. Where a residual current device (RCD) is used
for protection in case of direct or indirect contact, only
an RCD of Type B is allowed on the supply side of this
product. Otherwise, another protective measure shall be
applied, such as separation from the environment by
double or reinforced insulation, or isolation from the
supply system by a transformer.See also Application Note
Protection against Electrical Hazards.
Protective earthing of the frequency converter and the
use of RCDs must always follow national and local
regulations.

2.11 Extreme Running Conditions

Short circuit (compressor phase – phase)
Current measurement in each of the 3 compressor phases
or in the DC-link, protects the frequency converter against
short circuits. A short circuit between 2 output phases
causes an overcurrent in the inverter. The inverter is turned
off individually when the short circuit current exceeds the
permitted value (Alarm 16, Trip Lock).
For information about protecting the frequency converter
against a short circuit at the load sharing and brake
outputs, see the design guidelines.
Switching on the output
Switching on the output between the compressor and the
frequency converter is fully permitted. The frequency
converter is not damaged in any way by switching on the
output. However, fault messages may appear.
Mains drop-out
During a mains drop-out, the frequency converter keeps
running until the DC-link voltage drops below the
minimum stop level, which is typically 15% below the
frequency converter's lowest rated supply voltage. The
mains voltage before the drop-out and the compressor
load determines how long it takes for the frequency
converter to coast.
Danfoss A/S © 12/2015 All rights reserved.
2
(6 AWG) Al or 2 rated
2 2
23