Scully St-35c-120 el User manual

Scully ST-35C

Technical Manual

Multiple Point Overll Prevention

Control Monitor

Scully Signal Company 70 Industrial Way, Wilmington, MA 01887, USA • 800-272-8559 • sales@scully.com • www.scully.com

ST-35C - Technical Manual

Table of Contents

General

1.1 Description 4.

1.2 Technical Specications 6.

1.3 Accessory Equipment

Installation

2.1 Mechanical Installation 8.

2.2 Electrical Installation

2.3 Initial System Checkout 10.

2.4 System Operation 11.

Maintenance

3.1 Enclosure 12.

3.2 Corrosion Protection

12.

3.3 Control Module (Circuit Board) 12.

3.4 Module Replacement 12.

3.5 Indicator Lights 14.

3.6 Control (Bypass) Switch 14.

3.7 Junction Box and Plug & Cable Unit 14.

3.8 Fuses Replacement Description 14.

3.9 Troubleshooting 15.

Diagram Appendix

4.1 DWG 31412 – Outline Drawing – Control Unit Enclosure 16.

4.2 DWG 63039 – Outline Drawing – Sculcon Junction Box 17.

4.3 DWG 61441 – Wiring Diagram - Typical Loading Rack Control 18.

4.4 DWG 61442 – Mounting Diagram – Control Unit & Junction Box 19.

4.5 DWG 31306 – Internal Wiring Diagram – ST-35C-EL 20.

4.6 DWG 31307 – Internal Wiring Diagram – ST-35C-ELK 21.

4.7 DWG 61145 – Installation Wiring Diagram 22.

4.8 DWG 61406 – Installation Wiring Diagram, ST-35C/ST-47C 23.

4.9 DWG 61559 – Replacement Parts ST-35C-120 VAC 24.

4.10 DWG 61224 – Replacement Parts ST-35C-240 VAC 25.

ST-35C - Technical Manual

General

Page 4.

The ST-35C Control Unit is used for overll prevention at loading terminals. In most tank truck

loading applications, volume to be loaded into each compartment is pre-set via a pre-set meter.

Under normal conditions the pre-set meter shuts down the loading after the pre-set volume is

loaded. The liquid does not reach the overll sensor as it is set at a level higher than the rated

capacity of each compartment. However, if the liquid level goes above the rated capacity of a

compartment, Scully’s ST-35C Overll Prevention system detects this overll condition and shuts

down the loading. Thus, it acts as a secondary (emergency) shutdown system, primary shutdown

control being provided by the pre-set meter.

The ST-35C Overll prevention Control Unit interfaces with 5-wire optic sensors. It is typically used

for overll prevention on bottom loading or top loading vehicles. It can monitor multiple sensors

(i.e. multi-compartment vehicles). It is mounted at the loading rack/gantry and connects to the

vehicle via a Scully plug and cable assembly.

The system incorporates Scully’s unique and exclusive Dynacheck® concept. To ensure that it will

always detect an overll condition, the controller uses pulsed signals which continuously check the

entire system operation including the controller, wiring connections and sensors. If a sensor comes

in contact with liquid, or in the unlikely event of a system fault, the pulsed signals cease, and the

controller automatically signals for immediate shutdown of the loading operation.

The ST-35C uses intrinsically safe voltage and current to connect to Scully liquid level sensors and

provides control for external electrical devices by opening and closing relay contacts.

Scully loading rack overll protection monitors have been carefully engineered to provide reliable

and safe performance when installed in conjunction with related Scully equipment according to the

instructions in this manual. Adaptations of, and additions to this equipment such as the use of

multiple cables and plugs, loading arm position indicating switches, enclosure heaters and similar

peripheral devices may void warranties unless authorized in writing by Scully Signal Company.

Please contact Scully prior to performing any installation or maintenance not specically described

in this manual.

1.1 Description

The ST-35C is for use with Scully 5-Wire Optic Sensors, Model SP-FU series. It can monitor up to

twelve (12) of these sensors in a “series” signal path. If any one of the connected sensors senses

liquid, the ST-35C will respond to this “wet” condition; output relay contact opens, and red light

turns on. Although its typical application is monitoring of sensors mounted on multi-compartment

vehicles, it is also used for high level detection in storage tanks (tank farms). One relay output

contact is provided, which opens if any sensor detects liquid.

ST-35C is also used with vehicles equipped with Scully’s IntelliCheck® series or ONBOARD Overll

Prevention Monitors. It interfaces with 5-wire optic socket on these vehicles. The ST-35C Control

Unit has an explosion proof enclosure for mounting in locations that are classied as hazardous.

Multiple Point Overll Prevention Control Monitor

General

Page 5.

ON OFF All optic sensors are dry and the circuit is functioning properly.

Controller output is in permissive state i.e. permit to load.

OFF ON One or more sensors are wet or faulty or no connection to sensors, or

the circuit is malfunctioning. Controller output is in non-permissive state i.e. no

permit to load.

OFF OFF No power to the unit or Bypass Control Switch is in OFF or BYPASS position.

GREEN RED Condition

1.1.1 Model Designations

The ST-35C Controller is available in 120VAC or 240VAC models, with or without control (bypass)

switch.

Model sufx (E) = Explosion-proof Enclosure, (L) = Indicator Lights, (K) = Key Lockable Bypass

Switch.

1.1.2 Explosion Proof Enclosure

Sufx “E” in the model number indicates controller is in an explosion-proof enclosure suitable for

hazardous areas. Conduit holes are provided in the enclosure for electrical access. The installer

must install Exd cable glands (or conduit and seal ttings) according to local codes.

1.1.3 Indicator Lights

Sufx “L” in the model number indicates red and green indicator lights on the controller enclosure.

These lights indicate the following conditions:

1.1.4 Bypass Control Switch

Adding the sufx “K” to the model number adds a lockable three-position control switch to the

enclosure.

• In the ‘OFF’ position, there is no power to the unit.

• In the ‘NORMAL’ position, the unit will operate normally, with “dry” sensors causing the

output relay to become energized (i.e. closed output contact).

• In the “BYPASS” position, power to the unit is switched “OFF” and the normally

open relay contacts are bypassed to permit emergency operation of the equipment,

without overll protection.

For normal operation, this switch should always be set in the NORMAL position. The switch is

enclosed in lockable box to allow locking with a user provided padlock.

CAUTION: When in ‘BYPASS’ mode the controller and sensors are DISABLED

and the system does not provide overll protection.

ST-35C-120 EL Multiple-Point Controller in Explosion-proof Enclosure with Indicator Lights,

120VAC

ST-35C-120 ELK Multiple-Point Controller in Explosion-proof Enclosure with Indicator Lights and

Key-lockable Bypass Switch, 120VAC

ST-35C-240 EL Multiple-Point Controller in Explosion-proof Enclosure with Indicator Lights,

240VAC

ST-35C-240 ELK Multiple-Point Controller in Explosion-proof Enclosure with Indicator Lights and

Key-lockable Bypass Switch, 240VAC

Model Description

ST-35C - Technical Manual

General

Page 6.

1.1.5 Indicator Light on Control Module

An internal red LED light is provided on the control module for convenience in checking the output

status when the cover is open. The light is ON when power is applied and dry and functional

sensors are connected to the unit. Thus, the internal light is ON when external green light is ON.

1.2 Technical Specications

Degree of protection of enclosure IP65. The rating of the enclosure is negated if the holes in the

enclosure are unplugged/unscrewed or any holes are drilled into the enclosure.

The ST-35C control unit has been designed to be impact-resistant. Do not subject to excessive

mechanical or thermal stresses. Do not allow the unit to come in contact with aggressive

substances that may degrade the integrity of the enclosure.

The ST-35C may only be repaired by replacing the internal control module. The internal control

module is non-repairable.

Do not open when an explosive gas atmosphere is present.

Temperature Range -20°C to +60°C

Power Requirements 120VAC Models: 100 – 130 VAC, 50/60 Hz, 20VA Max.*

240VAC Models: 200 – 250 VAC, 50/60 Hz, 20VA Max.*

*20VA does not include circuits controlled by the output relay contact

Sensors: Up to 12 of Scully’s 5-wire optic sensors, Model SP-FU series.

Output Relay: One normally open volt-free contact rated 250VAC, 5A resistive max.

The output contact closes when all sensors are dry and functional.

Response Time: 0.5 second maximum

Indicator Lights: Output status indicator lights:

Red: Non-permissive

Green: Permissive

Output Control Fuse: Internal 5 Ampere

Connections: Provided by internal terminal strips.

Enclosure: Explosion-proof, weatherproof IP65.

Dimensions: See Appendix 4.1 for outline drawing.

Weight: 12.7 Kg (28 Lbs.)

Approvals: Baseefa02ATEX0047 Ex db [iaGa] mb IIB T5 Gb Ta=-40°c to +60°c

or Ex db mb [ia Ga] IIB T6 Gb

The enclosure contains associated electrical apparatus to

Baseefa02ATEX0148U [Ex ia] IIB (Tamb-40°C to +70°C) Gb