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PROGRAMMABLE PARAMETERS
The following settings MUST be programmed by the user in order to provide proper protection for
the application. All parameters are actual values except for the VUB and CUB settings; these are
programmed as percentages. The range each parameter can be programmed to is found on the
electrical specifications table on page 13. See page 8 for programming examples.
LV/HV
- The recommended settings for LV (low voltage) and HV (high voltage) according to the
NEMA MG1 standard are ±10% of the motors nameplate voltage. For other settings, the
motor manufacturer should be contacted.
Example:
The motor nameplate voltage is 230 volts. 90% and 110% of 230 is 0.9 x
230=207 volts for the LV setting and 230 x 1.1=253 volts for the HV setting. These
parameters are based on the average voltage going to the motor.
VUB/TS
- VUB (voltage unbalance) is factory set at 6%. The NEMA MG1 standard says a motor
should not be operated above a 1% voltage unbalance without derating
the motor. Most
utility supplied power sources have a difficult time sustaining a 1% VUB. The motor
manufacturer should be consulted for an exact VUB setting. A setting of 999 for VUB will
disable the VUB protection but will not disable SP (single-phase protection).
The VUB is calculated as follows:
%VUB = [(Maximum deviation from the average)/Average] x 100%
Example:
Measured line-line voltages = 203, 210, and 212, so the average =
(203+210+212)/3 = 208.3, the maximum deviation from the average is the biggest
difference between the average voltage (208.3) and any one voltage reading, 212-
208.3 = 3.7, 210-208.3 = 1.7 and 208.3-203 = 5.3, therefore the maximum deviation
from the average is 5.3. The VUB is then = 5.3/208.3 x 100= 2.5%.
The TS setting allows the user to turn the temperature sensor trip function on or off.
MULT
- MULT (multiplier) setting is found on Table 1. The MULT setting is determined by the
current the unit will be monitoring. This allows the unit to display the correct current.
Changing this setting will also change the UC, OC, and GF setpoints.
OC
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OC (overcurrent) is usually set at the service factor amperage (typically 100-115% of
motor FLA) of the motor, which is determined by the motor manufacturer. If any one leg of
current exceeds the OC setting, the unit will follow its overload trip curve (see Figure 4).
UC
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UC (undercurrent) is typically set at 80% of the full-load amperage of the motor. This is
usually adequate for protection of loss of load for many pumps and motors, including
submersibles. If the motor is not pulling near full load amperage then the UC may have to
be set to something higher than 80% of FLA for adequate protection. UC can be set to 0 if
UC protection is not desired. The UC trip point examines average current to determine if
an undercurrent trip condition exists.
CUB
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CUB (current unbalance) is factory set to 7%. SymCom recommends the motor
manufacturer be contacted for an exact setting. The CUB is calculated the same way the
VUB is determined above. The CUB protection can be disabled by programming a 999 in
this setting. This will disable current unbalance protection and current single phasing
protection.
TC
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TC (trip class) is the parameter used to determine when the unit will trip when an overload
condition is detected. For standard motors, the TC is typically set at 20. The motor
manufacturer should be contacted for exact TC settings. Table 2 and Figure 4 show the
TC settings and trip times.
