1. Motor / Transformer / Generator Switching Surge Protection Device
ZORC
Motor / Transformer / Generator
Switching Surge Protection Device
OVERVIEW PRESENTATION:
HIGH LEVEL PRESENTATION:
APPLICATION

2. Insulation Failure Costs
Cost of removing failed equipment from service, and for reinstallation after repair.
Cost of transportation to and from the site.
Direct repair cost.
Cost of downtime and lost production (or disruption to production).

3. Scope of Operation Spike description Amplitude 1-6 pu
Rise time .1-.2µ sec
Range
Voltage: 400V to 40 kV
Line Frequency: 50 – 60 Hz

4. Clamping of Switching Surges
Air circuit breaker closed Hz
Normal operation
Air circuit breaker Open
Switching off motor
Air circuit breaker Open Z O R C
Zorc clamping the spike

5. Transient effects on cablesCu Cu Cu

6. Three phase units separate or in one tank
Internal connections R C
Live terminal
Earth
Single phase
ZnO (>2.1 p.u)
Three phase units separate or in one tank

7. Benefits of ZORC
ZORC halves the magnitude of steep wave-front surges impinging on the load terminals by providing a matched cable terminating impedance under transient conditions, thereby eliminating refraction of steep wave-front surges (i.e. eliminates voltage doubling effects).
ZORC eliminates multiple pre-striking and re-striking transients associated with vacuum and other switchgear, by eliminating reflections of the pre-strike and re-strike current wave-fronts, and thus preventing high frequency current zeros in contact gap of the switch.
ZORC provides a suitably low absolute limit to the magnitude of steep wave-fronted surges that may impinge on the load terminals, and slopes that portion of the steep wave-front which exceeds this limit.
ZORC provides comprehensive insulation co-ordination, at all practical steep wave-front surge magnitudes and rise-times, within the motor impulse withstand levels recommended by the IEEE and CIGRë curves

8. Benefits of ZORC – Cont.
ZORC protects new motors and dry-type transformers throughout their service life by reducing the magnitude, rise-time and frequency of occurrence of steep wave-fronts impinging on the load terminals.
ZORC extends the life of motor and dry-type transformer insulation if retro-fitted to existing motors in service.
ZORC saves money by eliminating losses incurred as a result of insulation failures of motors and dry-type transformers, in terms of both direct repair costs as well as costs of down-time leading to lost or disrupted production.

9. Product Features
Compact
ZORC is compact enough to be fitted within most motor/transformer terminal enclosures or switchgear panels.
Low Cost
ZORC offers an unparalleled price/performance ratio.
Easy to apply
ZORC suppressors may be selected from a catalog with no detailed engineering required.
Motor/transformer mounting and switchgear panel Mounting versions
ZORC versions are available for both motor/ transformer mounting (M type) and panel mounting
(P type)
Single phase and three phase versions
ZORC suppressors are available as both single phase or three phase versions. Single phase versions are suitable for installing in phase segregated terminal enclosures.

10. Product Features Class 1 Division 2 Certification (ExN, non sparking)
As an option ZORC surge suppressors may be ordered certified for use in potentially flammable atmospheres (Class 1 Division 2 locations), temperature classes T1 to T5, to SABS (amended).
Easy to install
ZORC suppressors may be mounted in any orientation, and convenient mounting brackets or clamps are provided. (See dimension drawings).
Well proven
Many thousands of ZORC surge suppressors have been installed over the past 10 years, on motors, generators and transformers, solving the pressing problem of insulation failures and attendant repair and downtime costs.

11. Industries
ZORC suppressors have been installed in large quantities in the following industries:
chemical
petrochemical
underground mining (gold, platinum, coal, other)
surface mining (coal, copper, uranium, iron ore, other)
metal beneficiation (steel, stainless steel, gold, platinum, copper and uranium refineries)
power generation (generators, power station auxiliaries)
pumping (water pumping stations, oil pipelines)

12. Typical Applications
ZORC suppressors are applied in the following specific applications on motors, generators, and dry and oil immersed transformers and associated switchgear:
Fans
pumps
Compressors
mills
crushers
refrigeration machines
motor-generator sets
mine winders
conveyors
underground and surface mini-substations and mobile substations
generators
power station auxiliaries
arc furnaces
induction furnaces

13. ZORC Pictures

14. Installation At motor At panel Compact version
Any orientation clearance consideration
2,5mm² flexible lead
16 – 25mm² earthing
Surge arrestors where required
Watch vibration and water ingress

15. Testing Visual inspection: No bulging of tank; bushings ok ? ;
Check for oil leaks.
Capacitance between bushings and earth : 0.1µ to 0.2µ Farad.
No partial discharges are measured.
DC over potential test
28kVdc for 3/6 kV
47kVdc for 11kV

16. Comparison to other Methods
Surge arrestors
Surge Capacitors

17. Aggravating Factors Optimised insulation and surge suppression
co-ordination covering various devices in use
Unsuppressed switching surges
Wave sloping capacitor (1)
Metal oxide arrester (2) 1 2 3 4 5 6 7
Stalled trip
Motor with-stand level (Cigrë)
Zorc at panel
Switch-on
Stalled trip
Peak-to-peak volts
Switch-on
Zorc at motor terminals
0.2 1 2 3 4 5
Surge rise-time in microseconds
Notes: (1) Normally fitted with parallel metal oxide power arresters.
(2) Clamping voltage: peak-to-peak = 2 x peak-to-earth volts.

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ZORC
The End ...
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