Transformer Power Rating - Control Techniques Midi-Maestro User Manual

Transformer power rating

A single three-phase transformer may be able to
supply more than one Drive.
The power rating of the secondary winding must
exceed the nominal power rating of the motor.
When using a transformer with more than one
secondary winding, the power rating of the primary
must exceed the sum of the power ratings of the
secondary windings.
The secondary windings must be delta-connected.
(This is not essential for the primary winding.)
Control Techniques Ltd is able to supply
the appropriate transformers.
Three-phase AC supply
To calculate the necessary adjustments required for
each secondary winding, the following equation for Ps
(in ) must be used:
VA
( ( ) )
× × × ×
Ps = Paz 1.5
Where:
Paz =
{(Vm1 × Cm1) + (Vm2 × Cm2) + (Vmn × Cmn)}
Vm =
Maximum motor speed in rads/sec =
Cm = Nominal motor torque in Nm
1.73
=
( ( ) )
n + 2
Corrective factor when using more than one Drive
in parallel
n = Number of Drives
To calculate the total transformer power in
following equation:
P = P + P + ...P
t S1 S2
Where:
P = Power rating of secondary winding 1
S1
P = Power rating of secondary winding 2
S2
P = Power rating of secondary winding n
Sn
6
1 73 .
( ( ) )
+ +
n 2
/9.55
RPM
, use the
VA
Sn
Figure 7 Three-phase
connections
Single-phase AC supply
140 × 8/16 may be operated on a
Model
DCD
single-phase supply.
The transformer power rating may be calculated using
the equation:
( ( ) )
× × × ×
Ps = Paz 1.5
Where:
Paz =
{(Vm1 × Cm1)+(Vm2 × Cm2) + (Vmn × Cmn)}
Vm =
Maximum motor speed in rads÷sec =
Cm = Nominal motor torque in Nm
1.73
=
( ( ) )
n + 2
Corrective factor when using more than one Drive
in parallel
n = Number of Drives.
The secondary winding should be connected to pins 21
and 22 of the power connector.
Figure 8 Single-phase AC supply and ground
connections
16 +DC
17 M1
18 M2
19 -DC
20 20 Earth (Ground)
21 L1(Phase 1)
22 L2(Phase 2) AC supply
23 L3(Phase 3)
24 Ext Drive braking resistor
25 Ext Drive braking resistor
Power connector
supply and ground
AC
1 73 .
( ( ) )
+ +
n 2
÷9.55
RPM
16 +DC
17 M1
18 M2
19 -DC
20 20 Earth (Ground)
21 L1(Phase 1)
22 L2(Phase 2) AC supply
23 L3(Phase 3)
24 Ext Drive braking resistor
Power connector
Midi-Maestro and Maxi Maestro Drive