Toshiba Adjustable Speed Drive H3 Operation Manual page 87

DRIVE AND MOTOR OVERLOADS
The H3 features separate overload curves for itself and the motor. All H3s can output 110% of their rated
current continuously; current levels above 110% are considered overload . The drive overload is fixed: 100
HP and smaller H3's overload is 150% of their rated current for 120 seconds; 125 HP and larger H3's
overload is 130% for 120 seconds. The motor's overload curve is defined by Items 158, 159, 160, and
output frequency:
Item 158, ELECTRONIC THERMAL PROTECT LEVEL 1 - use this parameter to scale the motor overload
protection to a specific motor's amp rating. Can be entered in percent or in amps, depending on the setting
of Item 296, CURRENT UNITS SELECTION. For percent setting, divide motor full load amps by drive full
load amps and multiply by 100.
Item 159, OVERLOAD REDUCTION START FREQUENCY - The motor overload protection provided by the
drive is speed-sensitive by default. With default setting, a H3 at 115% of the current set by ELECTRONIC
THERMAL PROTECT LEVEL 1 will trip on MOTOR OVERLOAD sooner at 15 Hz than at 60 Hz. Users who
have allowed for reduced motor cooling at low speeds can reduce this parameter to get more overload
capability. The drive's overload protection is speed sensitive at frequencies below the value entered here.
Item 160, MOTOR 150% OVERLOAD TIME LIMIT - This parameter sets the time the drive will output
150% of the current set by Item 158, ELECTRONIC THERMAL PROTECTION LEVEL #1 before tripping
on MOTOR OVERLOAD.
Item 161, OVERLOAD SELECTION - This parameter adjusts the overload protection scheme.
0: Standard
1: Soft stall on. Soft stall reduces output frequency only when the drive is in its overload
region. Soft stall helps prevent drive from tripping on INVERTER OVERLOAD.
2: Motor overload trip off.
3: Soft stall on and motor overload trip off.
Motor overload sensing is "on" unless "2" or "3" is selected.
INVERTER OVERLOAD cooling time is approximately one minute after trip
MOTOR OVERLOAD cooling time is approximately five minutes after trip
DBR OVERLOAD cooling time is approximately thirty seconds after trip
Item 162, STALL PROTECTION ENABLE - Drive current limits when stall is turned "on".
Item 163, STALL PROTECTION LEVEL - Drive will reduce its output frequency and voltage automatically
to limit output current to the value programmed here.
Item 164, UNDERVOLTAGE TRIP SELECTION - The drive can be programmed to UNDERVOLTAGE TRIP
when the DC bus voltage is under a factory-set value by programming a "1" here. See Item 165 also. An
undervoltage alarm is available in the form of a drive output contact change; see Items 60, 63, or 66 and
setting values 24/25 on page 9-11.
Item 165, UNDERVOLTAGE DETECT TIME - The DC bus must be low for at least the time entered here
before the drive faults on UNDERVOLTAGE TRIP.
Item 166, LOW CURRENT DETECT SELECTION - The drive can be programmed to LOW CURRENT TRIP
when its output current is below the value programmed in Item 167 for at least the time programmed in
Item 168. Enter a "1" here to enable the low current detection. A low current alarm is available in the form
of a drive output contact change; see Items 60,63, or 66 and setting values 26/27 on page 9-11.
TOSHIBA
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