Page 99 - 2020 Catalog

TRANSFORMERS

Tips, Tricks and FAQs

Senva wants to ensure each product is used for the proper application. Below is a list of FAQs we encounter on a regular
basis with our current sensor lines. Remember, Senva offers live customer and technical support via email sales@ FREQUENTLY ASKED QUESTIONS
senvainc.com or toll-free (866) 660-8864.

LOOPING WIRE
Technicians can loop wires in order to increase the amount of current passing through the CT. Each loop doubles the
amount of amperage passing through the CT. This may be required for applications where not enough amperage is
present in a single wire to fall within the specified CT amperage range.

LOAD SIDE VS. LINE SIDE
All Senva Fixed, Preset, Autoset, Multi-point and Analog current sensors are designed to go on the line side of the motor/
pump as all of these CTs operate at a frequency of 50/60Hz. The VFD line (C-2350VFD & C-2350VFD-L) and C-1550 are the
only CT lines that are designed to be installed on the load side as they are looking at the ratio between amperage and
frequency.
MONITORING STATUS

When monitoring status on your pump or motor, utilize a fixed current sensor that has a minimum threshold of 0.5A
or lower. Fixed current sensors will close the contacts and relay a signal that current is present in the line to the pump/
motor.

MONITORING BELT LOSS/COUPLING
When looking for belt loss/coupling there are several options based on the desired signal. For a digital current sensor
on constant volume motors/pumps, utilize the Preset or Autoset line. The preset line allows the electrician or technician
to set the dial to the full load amperage (FLA) on the motor name plate. The Autoset line uses a microprocessor to
automatically set the threshold in the same fashion as the Preset without requiring any manual adjustment. The sensor
then looks for a 30% or greater decrease in amperage to alert when a belt has broken.

When working with direct drive or fractional HP motors/pumps, it is often recommended to utilize an analog CT as the
change in amperage between a loaded and unloaded motor may be too small for a digital current sensor to detect and
trigger the alarm.

When working on variable frequency drives (VFDs) see below for the Senva VFD specific sensor.

VFD APPLICATIONS
Our most frequent technical call regarding our current sensor line is for misapplication using our VFD sensors. New for
2019 is the Autoset series which will work on both VFD and constant volume applications for proof of flow. This is a self-
learning sensor with and improved lower turn on.

ISSUES WITH MONITORING STATUS ON ELECTRONICALLY COMMUTATED MOTORS (ECM)

ECMs draw a small amount of AC current to the inverter, up to 120mA, when the motor isn’t running. If you’re using a
fixed current sensor with a extremely low trip-point, it may falsely indicate the motor is running when in fact it is only
passive current draw from the inverter. See the new ECMset current sensor with adjustable turn on to be set above the
ECM stand-by current.

Higher Reliability, Faster Installation, Superior Accuracy | Sense the difference | 99