K. S. Instruments Private Limited

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KSI make Neutral Grounding Resistors are rated in line-to-neutral voltage
(system voltage divided by 1.732), initial fault current and maximum on time.
KSI Grounding Resistors are designed to dissipate the required power without
the temperatures rising above the limits set by the IEEE 32-1972 standard. The
time and temperature ratings for Grounding Resistors are as follows:
Short Time: Short time is referred for a period more than 10 but less than 60
seconds. These are generally used with Fault Clearing Relays. The short time
temperature rise is 760¿c.
Extended Time: A ¿Time on¿ rating greater than ten minutes is referred as
Extended time but also limits the average usage of not more than 90 days per year.
The extended temperature rise is 610¿C.
The drive manufactures normally determines the power rating (watts) needed to prevent
overheating during braking duty. The peak braking current is determined by the specified
resistance value. The braking torque is usually specified as 100% or 150%, which is a function
of the ohmic value of the resistor. Higher braking torque means lower resistance, higher
braking currents and faster motor stops Each drive manufacturer specifies a resistance range
with a minimum to present over current and damage the drive and a maximum value to
give adequate lower dissipation capability.

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