Digidrive SK Technical Data
29
Issue Number: a www.leroy-somer.com
11.4 Fuses
The AC supply to the drive must be fitted with suitable protection against overload and short circuits. Tables 1-2 & 1-7 show the recommended fuse
ratings. Failure to observe this requirement will cause risk of fire.
A fuse or other protection device must be included in all live connectors to the AC supply.
An MCB (miniature circuit breaker) or MCCB (moulded case circuit breaker) with type C tripping characteristics maybe used in place of fuses as long
as the fault clearing capacity is sufficient for the installation.
Fuse types
Europe: Type gG HRC fuses complying with EN60269 parts 1 and 2 (BS88)
USA: Bussman Limitron KTK series, class CC fast acting fuses up to 30A, class J above 30A.
11.5 Ground connections
The drive must be connected to the system ground of the AC supply. The ground wiring must conform to local regulations and codes of practice.
The ground loop impedance must conform to the requirements of local safety regulations. The ground connections must be inspected and tested at
appropriate intervals.
Use of RCDs - residual current device
There are three common types of RCD/ELCB
Type AC
- detects AC fault currents
Type A
- detects AC and pulsating DC fault currents (provided the DC current reaches zero at least once every half cycle)
Type B
- detects AC, pulsating DC, and smooth DC fault currents
•
Type AC should never be used with inverter drives
•
Type A can only be used with single phase drives
•
Type B must be used with three phase drives.
It is recommended that only Type B RCDs be used with inverter drives
If an external EMC filter is used, a delay of at least 50ms should be incorporated in the RCD to ensure spurious trips are not seen. The leakage
current is likely to exceed the trip level if all of the phases are not energised simultaneously.
11.6 Ground leakage
The ground leakage current depends upon the internal EMC filter is fitted. The drive is supplied with the filter fitted. Instructions for removal of the
internal EMC filter are given in Section 4.3.1 of the getting started guide.
With internal EMC filter fitted
Size A
10mA AC at 230V, 50Hz (proportional to supply voltage and frequency)
Size B and C
1 phase 200V product
20mA AC at 230V, 50Hz (proportional to supply voltage and frequency)
3-phase 200V product
7mA AC at 230V, 50Hz (proportional to supply voltage and frequency)
3-phase 400V product
8.2mA AC at 415V, 50Hz (proportional to supply voltage and frequency)
30µA DC (10
Ω
)
N
The above leakage currents are just the leakage currents of the drive with the internal EMC filter connected and do not take into account any leakage
currents of the motor or motor cable.
With internal EMC filter removed
<1mA
N
In both cases, there is an internal voltage surge suppression device connected to ground. Under normal circumstances, this carries negligible current.
When the internal EMC filter is fitted, the leakage current is high. In this case, a permanent fixed ground connection must be provided
using two independent conductors each with a cross-section equal to or exceeding that of the supply conductors. The drive is provided
with two earth terminals to facilitate this. The purpose is to prevent a safety hazard occurring if the connection is lost.
NOTE
NOTE
WARNING