Calculation Of Resulting Reference - Danfoss VLT 4000 VT Instruction Manual

Calculation of resulting reference

The calculation made below gives the resulting
reference when parameter 210 Reference type is
programmed for Sum [0] and Relative [1], respectively.
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Ana. signal Te r
Ext. ref.
m. 53 [V]
Par. 310 Term. 53 Max. scaling - Par. 309
=
Term. 53 Min. scaling
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Par. 314 Term.
60 [mA]
Par. 316 Term. 60 Max. scaling - Par. 315
Term. 60 Min. scaling
Par. 210 Reference type is programmed = Sum [0].
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Par. 211-214
Res. ref.
Preset ref.
=
Par. 210 Reference type is programmed = Relative [1].
External reference x Par. 211-214 Preset ref.
Res.ref. =
Galvanic isolation (PELV)
PELV offers protection by way of extra low voltage.
Protection against electric shock is considered to be
ensured when the electrical supply is of the PELV
type and the installation is made as described in
local/national regulations on PELV supplies.
In VLT 4000 VT all control terminals as well as
terminals 1-3 (AUX relay) are supplied from or in
connection with extra low voltage (PELV).
Galvanic (ensured) isolation is obtained by fulfilling
requirements concerning higher isolation and
by providing the relevant creapage/clearance
distances. These requirements are described
in the EN 50178 standard.
For additional information on PELV see RFI switching.
The components that make up the electrical
isolation, as described below, also comply with the
MG.40.A7.22 - VLT is a registered Danfoss trademark
100
+
100
VLT
External reference is the sum of references from
terminals 53, 54, 60 and serial communication.
The sum of these can never exceed parameter
205 Max. reference. External reference can
be calculated as follows:
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Ana. signal
Term. 54 [V]
+
Par. 313 Term. 54 Max. scaling - Par. 312
Term. 54 Min. scaling
+ serial com. reference x (Par. 205 Max. ref. - Par. 204
Min. ref.)
16384 (4000 Hex)
External ref. + Par. 204 Min. ref. + Par. 418/419
+
Setpoint
Par. 204 Min. ref. + Par. 418/419 Setpoint (only in closed
loop)
requirements concerning higher isolation and the
relevant test as described in EN 50178.
The galvanic isolation can be shown in three
locations (see drawing below), namely:
1. Power supply (SMPS) incl. signal isolation of U
indicating the intermediate current voltage.
2. Gate drive that runs the IGTBs (trigger
transformers/opto-couplers).
3. Current transducers (Hall effect current transducers).
NOTE
525-600 V (VLT 4002-4072) units do not
meet PELV requirements.
Galvanic isolation
®
4000 VT
(only in closed loop)
,
DC
123
+