King Electric GPT 3 - Manual (Page 7)

Page 7 of 21
Safety
Make all electrical connections in compliance with the National Electric Code (NFPA 70)
and local electrical code. If you have questions concerning the installation or application, contact
Customer Service.
Contacting Environmental Technology
For assistance, contact Customer Service. Office hours are 8:00 AM until 5:00 PM EST
(UTC minus five hours).
Voice: (800) 234.4239 (USA and Canada) or (574) 233.1202 (elsewhere)
Fax:
(888) 234.4238 (USA and Canada) or (574) 233.2152 (elsewhere)
E-mail: [email protected]
Mail:
Environmental Technology, Inc.
1850 North Sheridan Street
South Bend, IN 46628
General
Introduction
The GPT–3 Freeze Protection Thermostat has a calibrated adjustment range of 41° to 77°F
(5° to 25°C) with a control band of 2°F (1°C). Heaters operate at ambient temperatures below the
set temperature.
The GPT–3 combines temperature control using either constant wattage or self-limiting
heaters with GFEP (ground fault equipment protection) and advanced monitoring features. For
example, although the GFEP is factory set to trip at 30 mA, this threshhold can be set to 60,
90 or 120 mA to cure nuisance tripping problems. Keeping wet fire sprinklers from freezing is
considered to be a higher priority than interrupting heater power in the event of a ground fault
condition. The GPT–3 accommodates this requirement by allowing the GFEP to be set only to
alarm while the ground fault persists.
Other features include continuous heater monitoring with separate modes for constant
wattage and self-limiting heaters. A trickle current verifies heater continuity of both heater
types when there is no call for heat. The current flow through constant wattage heaters verifies
continuity during operation. Self-limiting heaters employ an independent temperature monitor
sensor (included) to measure the hot-end temperature. Depending upon how long it takes the
cable to reach its operating temperature such that the monitor sensor is less than 5°F (3°C) below