Siemens LMV5 Quick Start Manual page 136

VSD Control
The LMV52 has the ability to control different types of VSD (variable speed drive).
The most common type of VSD used with the LMV52 is the VFD (variable frequency drive), and the
most common type of motor used with the VFD is the so called "synchronous" AC induction motor.
For a more in depth overview of this application, please see the fist few pages of Section 7-1.
Common problems and the related solutions include:
VFD will not operate
If the VFD will not operate the blower (blower will not spin) when the LMV52 parameter standardize
is activated. Consider the following:
1) Verify that the following:
a. The 0 / 4-20mA signal from the LMV52 to the VFD is wired correctly
(LMV52 terminals X73.4 and X73.2).
b. The run / stop contact is wired to the VFD correctly
(LMV52 terminals X73.1 and X73.2)
c. The VFD parameters are set for the motor that it driving.
d. The VFD is spanned so that 0 or 4mA equals 0Hz and 20mA = 63Hz
(60 Hz grid frequency). The reason for this is explained in Section 7.
e. VFD is in remote mode so that it looks for a 0 / 4-20mA signal, and run / stop
contact. Closing the contact should cause the VFD to operate the motor.
f. Verify that the three-phase wiring between the VFD and motor is correct.
2) Disconnect the analog signal and run / stop contact wires between the VFD and the LMV52.
Use a handheld 0 / 4-20mA source and a toggle switch to verify
that the VFD responds to a contact closure and a varying 0 / 4-20mA signal.
If the VFD does not respond, check / correct the configuration of the VFD.
If the VFD responds to the contact closure and the varying 0 / 4-20mA signal,
then go to the next step.
3) With the wires between the LMV52 and VFD still disconnected,
use a multi-meter to verify that the LMV52 outputs about 19.5mA during the standarization,
(see note below) and that the run-stop contact (dry contact) in the LMV52 closes,
and remains closed during the standardization.
If there is no analog signal, and the contact does not close, verify that the VSD is set to
activated under : Params & Display > Ratio control > Gas / Oil settings VSD.
Also ensure that the safety loop (X3-04 Pin 1 and Pin 2),
and the burner flange (X3-03 Pin 1 and 2) are closed.
Note: When standarization is activated in the LMV52, the air actuator should drive to
prepurge position before the run / stop contact closes and the LMV52 puts out
19.5mA. This is done so that the blower motor has a representative load (blower
moves air) during standardization.
If this does not happen automatically, make sure that the air actuator is set to air
influenced and the safety loop is closed.
Depending upon what air actuator is used and what parameter "TimeNoFlame" is set
to, the actuator could take up to 120 seconds to reach prepurge position.
4) If the VFD responds to a contact closure and a 0 / 4-20mA source,
the VFD should be configured correctly.
If the LMV52 closes the run / stop contact and produces 19.5mA when put into standardize
mode, then the LMV52 should be configured correctly.
Thus, the LMV52 / VFD / motor combination should operate properly,
and standardize when wired back together.
LMV5 QSG Rev 4
The LMV5 will not standardize if an alarm is present.
Sec 5 Pg 10 www.scccombustion.com