870 Series SCR Control Panel
The 870 Series SCR Control panel is a fully proportional process temperature control panel that utilizes SCR Power Controllers to modulate the entire heater load directly, varying the heater output from 0 to 100% of the total heater KW. Working on a four second time base, the heater will be energized only for the number of AC cycles necessary to produce the exact amount of heat required. The resulting precise control and rapid response make the 870 Series SCR Control Panel the best choice for applications that must accommodate material flow changes and still provide precise temperature control. The panel is completely assembled, pre-wired, tested, and ready for troublefree installation and operation. Designed for use in industrial environments and outdoor installations.
UL Listed/CSA Approved
NEMA 4/12 painted steel enclosure1
PID self-tuning temperature controller (adjustable process temperature with standard type “J” thermo-couple input)
Over-temperature controller (adjustable temperature limit with standard type “K” thermocouple input)
Disconnecting 50 amp safety contactor for resistive loads (per circuit)
120 VAC control power transformer with primary and secondary fusing
Power circuit fusing
Three-phase, zero cross-fired SCR power controllers
Door interlocking disconnect switch
Manual reset pushbutton with built-in pilot light (red) for “OVER-TEMPERATURE” alarm
Selector Switch – ON/OFF with built-in pilot light (green) for “POWER ON” indication
Terminals for customer supplied remote interlock
Wiring diagram permanently affixed to the inside of the cover
Short Circuit Current Rating of 5KA
These relays are activated by safety devices, such as a flow switch or remote shutoff.
Additional indicator lights may be specified for visual indication of system status, such as “LOW TEMPERATURE”.
Audible Alarm Package
Includes a horn, pilot light, latching relay and a push button for silencing the horn.
Low Liquid Cutoff
The relay is mounted and wired with sensing probe shipped loose for field installation.
This package consists of a motor starter for pump motor start-up. Motor starter is internally mounted and field connected to the pump motor.
The customer may specify the use of special process or over-temperature controllers for a different temperature range, sensor input, control mode, etc.
A heater and thermostat are provided to prevent condensation and maintain minimum ambient temperature for electrical components.
Identification markers are attached to both ends of all control and power wires.
Tagging of Internal Parts
Permanent tags are attached to the subpanel near internal parts and marked with component titles as noted on the wiring diagram.
A cast aluminum enclosure is rated for Class I, Groups C & D and Class II, Groups E, F & G (NEMA 7, 9).
Type Z for Class I, Division 2 areas Type X for Class I, Division 1 areas.
Optional Temperature Inputs
Type “K” thermocouple inputs or “RTD” inputs.
Stainless Steel Panel Enclosure (NEMA 4X)
This con-struction provides extra corrosion resistance for harsh environments1.
(1) Agency listed for NEMA 4 only.
65 KA interupting amp rating.